Historical monuments and properties have always been highlighted in the course of history as heritage artefacts. Not only have their physical and historical aspects been important, but also they have carried messages and values from the past and have expressed beliefs common in traditions of different periods as well as all various human activities influenced by different historical, cultural, geographical and social factors. They have functioned as bridges linking the man to the past. Historical properties have sustained numerous small and big damages due to natural or manmade reasons. Restoring or repairing historical monuments and properties have always been important for the man and some efforts have been taken to intervene and restore these monuments. In every restoration, at least two elements can be easily distinguished, “the item of restoring” (monuments and things) and “human factor in restoration” (restorer). By referring to history of restoration and analyzing restoring theories and attitudes, it can be said that there was always more attention to the item of restoring than the restorer. In these processes, restorers have merely been looked at as executors of guidelines and theories and no specific definitions have been presented about restorers and the procedures for assessing their performances. In light of the huge number of existing conservation and restoration theories, and considering the fact that any measures taken for cultural heritage and artefacts are inevitably bases on theories and any conservation and restoration is presumably founded on experiences and skills, lots of emphasis have been placed on preserving authenticity, historical and physical values of properties and their materials. Most of guidelines and instructions have been drafted based on this view. However, in the course of time, some new theories have emerged and accordingly other documents have highlighted conceptual and intangible aspects of the heritage. The present paper intends to review the history of restoration and roles of restorers across the history.

Early Medieval Period and Middle Ages

During the heyday of Greek and Roman civilizations, known as classical civilizations, new ideas were born, the first foundations of philosophy emerged and the art rose to its pinnacle. Artworks were created based on ideas of idealism and imitations from the nature. These ideas were directly influenced idealistic thought of Plato. The more perfect the imitation made from the nature, the better the artworks emerged as specific attention was paid to three distinctive features and pillars of the classical period namely beauty, proportion and truth. The physical integrity of properties was considered as very important factors for Greeks and they liked properties to return to their primary shapes. Observance of this principle led to creation of a perfect artworks. With the observance of idealistic beauty and proportion as essential components of beauty, properties gained prominence. If proportionality was not observed, properties would look unpleasant. During this period, some previously-made bronze statutes were occasionally melted to create proportion and bring them closer to realities as much as possible. To do so, these destroyed properties were restored or reconstructed to bring them closer to original status while observing principles of proportion and beauty. Rome and Romans were so influenced by the ancient Greek art and the philosophy of idealism that they reconstructed artworks with the view of observing three aforesaid traits, i.e., beauty, proportion and truth. The main criterion for restoration of properties was their revitalization. In line with this approach, Romans reconstructed or restored propertied that had been destroyed or damaged.

Renaissance (14^th-16^th Centuries A.D.)

The Renaissance was period when the man got the chance to know himself and to look at the world through a perspective different from that of the Middle Ages. The Renaissance refers to an intellectual movement that originated from the northern European cities in the 14^th century, reached its summit in the 16^th century and came to an end in the U.K. after about 300 years. The first sparkles of formation of the Renaissance came to surface in the mid-13^th century through independent intellectual movements.

The religious reform was one of the most important movements during the Renaissance that led to prosperity of scientific, artistic and philosophical views. During the Renaissance, the idea of historical recurrence was formed in Europe and some scientists, poets, and philosophers emerged who were inspired by the original heritage of Rome and Greece but they looked at the world through a fresher view. They were familiar with the process of historical transformation. Historical works that had been abandoned from the Middle Ages turned into inspiration sources for artists. During the Renaissance, historical properties were considered as the manifestation of arts and arts were free adaptations from these historical properties. Consequently, artistic and historical aspects got unified meanings.

Another essential principle was the aesthetical aspects of properties that were defined based on tastes and thoughts of restorers. It was believed that the authenticity of restoration lies in the conceptual patterns. This view resulted in emergence of a new trend in restoration of historical properties. Accordingly, broken items and properties were preserved to protects their aesthetical integrity and to use them for educational purposes. Similarly, the imperfect properties were reconstructed to return to their previous forms. Restorers did not intend to intervene in properties and their actions were mainly conducted as complementary measures. Therefore, it was considered to be normal for restorers to decrease the original volumes of properties in restoration processes for the sake of their beauties or annex some elements thereto.

When the Renaissance began, religious beliefs and biases were modified, philosophical views and thoughts of Aristotle and Dante gained momentum and intellectuals such as Francesco Petrarca, commonly anglicized as Petrarch with his ideas of humanism emerged. The restoration procedure was a completed form of restoration thoughts of the Middle Ages. One of the important features of the Renaissance was its impacts on the concept of the art. Then, historical objects were reviewed in restoration debates both as artworks as well as antiquities. Hence, a new understanding was formed about artworks that guided artists to exalted positions during this period.   Unlike the Middle Ages, during the Renaissance some attention was paid to old documents and consequently, documentation of properties became popular. When monuments were destroyed, damaged or razed, only some documents or maps or occasional models remained after them.

Using pieces of old objects for repairing statues and completing new ones, Romans appeared as pioneers of new restoration methods in Europe in the 15^th and 16^th centuries. During this period, restoration turned into an ordinary activity of making statues and it was considered as a test for proving the level of expertise. Similarly, restoration was regarded as an important endeavor similar to architecture and restorers were attached a status similar to that of architects. The Renaissance was the beginning of the restoration age for artworks and cultural properties. This trend continued to the 18^th century and its overall principles were defined.

In the late 16^th century, a new transformation emerged in the Renaissance art and literature that was called the Baroque Movement. The Baroque Movement of Italy was influenced by the anti-religious reform movement which was extended to much of Europe. In the Baroque Movement special and valuable status was assigned to restoration and restorers. During this period, the originality of restoration lies in its potentiality to become prominent. Logically-speaking, restoration is considered as a measure at the service of properties. Contrary to this general axiom and interpretation, properties served restoration during the Baroque Movement whereby restoration was conducted in a way to look more prominent. As a result, more attention was paid to restored or added parts rather than properties themselves. As restoration was more important than properties during the Baroque Movement, naturally restorers held more valuable position compared to that of the original creators of artworks. In fact, tastes, thoughts and ideas of original authors were not given respect as it was required and they were not regarded as instructors or trainers.

Romanticism (late 18^th century)

On the heydays of the Enlightenment Age in Europe in the 18^th century, a philosophical movement was formed that was dominant over other ideals and thought of that century. Neoclassicism and romanticism lived and prospered in a parallel fashion in this century.

Romanticism is related to the history of modern art and it has gone beyond the framework of classical traditions and covenants. Semantically-speaking, romanticism was used in the 17^th century in England to describe poetic interpretations. Then, romanticism spread to France, Russia and Spain and finally dominated over the literature and art of Europe where lots of authorities and authors expressed their ideas within the framework of romanticism as a new modern form of art to distinguish themselves from the classical art. Expressing emotions and feelings is one of the principles of a romantic artist.

During the age of romanticism, restorers try to gain information about history, and pay attention to national values and physical features of properties without dealing with details so as that they reconstruct damaged parts of properties to make them as close as possible to the initial whole. Therefore, it is incumbent upon restorers to increase their knowledge about missing parts of artworks through historical studies.

Another tenet and distinct feature of the age of romanticism is its interest in Christianity. Artists of this period paid studios attention to religions as they needed to take into account their spiritual needs and make use of emotions to move towards faith.

During the age of romanticism, restoration of historical monuments and properties go beyond its old limits and some special facilities are provided for assessment of restored works. Thanks to activities of critics and philosophers and developments of ideas, theories that completed previous theories reaches to their apexes through experience, criticism, guidance, compiling theories and inventing methods. These theories and methods have continued to now and have left impacts on modern ideas, theories and charters on conservation and restoration of historical monuments and properties.

Nineteenth century

Developments of the 19^th century, sociopolitical conditions and advancement of sciences and technologies in the late 18^th century set the grounds for birth of numerous new ideas, thoughts and movements. These changes led to development of new styles, concepts and principles in these fields that set the ground for intellectual, philosophical and ceremonial developments in the sphere of restoration and conservation in the 20^th and 21^st centuries.

The intent of anastylosis is to rebuild, from as much of the original materials that is left after years of abuse, historical architectural monuments which have fallen into ruin. This is done by placing components back into their original positions. Anastylosis Movement changed romantic interpretation of historical monument and objects. Advancement in sciences and technologies as well as emergence of positivism left their impacts of these transformations, too. Emergent historicism changed attitudes and views. Anastylosis was created under the influence of writers, artists and authorities of the 19^th century including a French architect, Eugène Emmanuel Viollet-le-Duc. In the 19^th century, historical monuments were looked at as national landmarks and their restoration was undertaken at the most appropriate manner and under a specific style. Aiming at integrating the monument, restoration was executed in a specific style. Some competencies required by restorers at that time included paying attention to artistic values and understanding various styles and age requirements of different historical periods. Restorers were required to make use of their scientific, critical and technical abilities for the sake of understanding characteristics of any period and style. According to this approach, restorers themselves need to be architects.

Conservation Movement

Criticisms raised by advocates of anti-restoration movement against restoring architects for their faults in ruining authenticity of monuments led to emergence of the Conservation Movement. John Ruskin was the pioneer of this movement.

Scientific conservation

During this period people were inclined towards developmental and systematic restoration of past monuments and properties as new theoreticians entered the field of restoration and conservation and they defined values, capacities, needs and requirements of restoration. Simultaneously, the first technical organizations for conservation and restoration of historical monuments and landmarks were established that were mainly public institutions and organizations engaged in undertaking scientific and executive affairs in this important field. As a result of these developments, a new phase ushered in for conservation and restoration during which different expertise and authorities such as chemists and physicists entered this discipline. Consequently, researches on historical and artistic remnants of the past were given their right status. From the late 19^th century to the early years of 1930s, some events transpired that led to enormous advancements in the domain of restoration. Establishment of the first restoration laboratory in Berlin in 1883, recruitment of a chemist as the restorer at Berlin museum and development and advancement of laboratory, scientific and positivistic methods contributed dramatically to conservation and restoration of artistic and historical properties. Some serious debates tool place between advocates of two dominant schools of restoration. The most famous theoretician with critical views was Winckelmann who was not directly engaged in architecture but his ideas left enormous impacts on restoration and conservation methods and techniques.

Irrespective of numerous conflicts existing among different theories and methods in the field of restoration and conservation, one can generally classify them into three main conceptual, philosophical, and methodological approaches as follows:

1. Restoration activities that were conducted since the early history of restoration by making use of various methods and different philosophical theories and were in line with emotional, aesthetical and historical approaches. Some of these artistic movements include classicism, romanticism and historical and archeological restoration that were influential in implementation of restoration methods. According to this approach, knowledge and expertise in the field of restorations are the most important features of restorers. Advocates of this approach maintained that knowing the history of art and following various restoration views and methods would improve the quality of conservation. They asserted that the physical dimension of properties should be prioritized over their artistic aspects.
2. The second category of approaches has some commonalities with the first one; however, they follow different intellectual and philosophical theories that emerged in the 19^th century as a consequence of extreme return to scientism. According to this approach, artifacts and properties are identified on the basis of experimental sciences and pure sciences. Followers of this line of thought believed that restoration follows rubrics of positivistic scientific methods. Hence, only the physical aspect of artifacts would be subject to this methodology. The most prevailing methods used in this approach were laboratory and quantitative methods. However, acquisition of knowledge on the art history and skill developments by restorers was important, too. Generally-speaking, physical dimensions of artifacts were prioritized to their artistic aspects.
3. The third approach gained momentum as of the early 18^th It was founded on ideas of Augustus Pugin and gained maturity in the 20th century by ideas of Cesare Brandi and philosophical views of Heidegger. According to this approach, restoration works are regarded as artworks. Therefore, they can be analyzed form artistic and physical perspectives. From the physical perspective, the technical, historical or skill-oriented knowledge and features of properties are historically studied. Unlike the artistic orientation, in this approach objects are reviewed based on phenomenological methods. However, these objects are analyzed artistically, too. Accordingly, restoration is looked at as an artistic endeavor where expertise and skills of restores are the main tools for preservation of artistic values of objects as well as their integrity. At this stage, the artistic aspects are given priorities over physical ones.  Special attention is paid to views and ideas of restorers about values and artistic features of properties and monuments. Advocates of this approach believe that all of restorers are not capable enough to fathom out artistic values. The quality of restoration is highly influenced by expertise and skills of restorers.

Following introduction of theories of Ruskin and Viollet-le-Duc in the early years of the twentieth century as well as establishment of the Conservation Association by James Morris and others, theoreticians entered this field by proposing their ideas on conservation of properties and monuments, and their values, descriptions and classifications. Emergence of philosophers such as Nietzsche and Heidegger as well as restoration theoreticians such as Brandi with his novel thoughts and orientation for distinguishing ordinary works and artistic ones, restoration views underwent huge transformations, restoration methods and theories inclined towards conservation and lots of attention was paid to non-physical aspects of properties and monuments. Brandi made a distinction between ordinary works and artistic ones. According to Brandi, an artwork can be restored on the basis of an aesthetical view and in line with its relationship with the object. Therefore, restoration is not merely based on tastes. Restoration is related to special artistic features of artifacts. Artistic features of objects confine the restoration and not the other way round. As a staunch advocate of self-specialty of artifacts, Brandi claimed that artworks are results of unique and creative processes. He believed that in any restoration, we should take into account special understanding of objects as artistic objects and special products of thoughts. He asserted that conducting restoration relied on this understanding. With the emergence of post-modern thoughts in the late 20^th century, all views and attitudes changed and later in the 21^st century a new definition of cultural heritage and understanding cultural and historical properties was created. Consequently, the status of restoration was transformed completely and a special meaning and importance was attached to conservation in lieu of restoration.  During this era, numerous theories, charters and new laws were presented. Additionally, some guidelines were developed for appropriate implementation of conservation pertaining cultural heritage.

Conservation as a science

Conservation is an activity performed on cultural-historical properties and objects for their efficient preservation and survival. Conservation and restoration are practical measures taken as preventive and treating actions in the field of cultural heritage. Procedures and scopes of conservation and restoration are affected by having a comprehensive understanding of objects and their essence. On the one hand, restoration is regarded as a technical-artistic approach since it is performed on damaged objects. On the other hand, it is looked as a scientific approach focusing on chemical and physical characteristics since it deals with chemical and physical features of materials. It is necessary to gain a comprehensive understanding of properties to conduct restoration. Understanding historical properties can determine the scope of restoration operation and its procedures. In fact, gaining this understanding is the most essential stage before any interventions. having a full-scale understanding about properties and objects is the prerequisite of any scientific restoration that leads to effective, lasting and efficient conservation. At the professional level, conservation can be looked at as a mixture of theoretical knowledge and practical skills.

As it has been defined in theoretical discussions, restoration can take place when there is some understanding about the artifact. Any objects that exists presently belongs to the past and it is part of that past. In performing conservation, one cannot suppose that time is reversible. Considering the historical complexities of properties, restoration cannot take expand without connections to time. Hence, it is necessary to understand issues such as time, past, present, and status of existence of objects in order to gain understanding about the true essence of properties and to plan a scientific restoration operation.

Causes of damages and restoration:

Generally, materials composing objects are categorized into two main groups namely organic and non-organic (mineral). Materially-speaking, organic materials are weaker than non-organic materials and they are more prone to natural degradation. To put it simply, one can assert that gradual decay and decomposition of organic materials occur faster than non-organic materials. The degradation rate means the speed or rate of destruction or degradation over a specific time period.

Generally-speaking, there are there types of degradation as follows:

1. Physical degradation:

Appearances of objects undergo some changes due to physical and mechanical forces such as sawing, breaking and grinding

2. Chemical degradation:

Different chemical factors cause internal changes in materials and their degradation or decay, e.g. high level of acidity in papers

3. Biological degradation:

In this type of degradation, external biological factors damage materials. Different fungi and insects damage materials such as papers, woods and cloths. These factors together with other instrumental elements such as darkness and nourishing sources provide a suitable environment for growth of these detrimental elements that play enormous roles in destruction of these materials.

Different objects could be exposed to various types of threats in every location and situation. To conduct restoration, one needs to get familiar with destructive factors and then embark on restoration in light of types of damages and materials. Main causes of degradation are as follows:

• Humidity: The amount of water vapor per cubic meter volume of air regardless of the air’s temperature is called absolute humidity. The amount of water vapor content in the air changes as temperature changes and this is referred to as the relative humidity. The volume of relative humidity changes in the opposite direction of temperature changes, that is, when temperature increases the relative humidity decreases and when temperature goes up, the relative humidity goes down. The humidity fluctuation leads to destruction of artistic and historical properties and artifacts. Organic materials such as woods, ivories, and papers experience changes in appearance when exposed to humidity since their cellular textures changes. Humidity fluctuation causes expansion and contraction which are manifested as twisting, bulging, and wrinkling. When exposed to humidity, non-organic (mineral) materials are broken and destroyed. Some of the effects of humidity on different materials include paste degradation, starch decay, ink disappearance, leather molds, papers sticking together, canvas stretching, leaving stains on papers and leathers and corrosion of metals. Additionally, humidity provides a pleasant environment for various fungi, bacteria and bugs to grow and activates lots of chemical reactions that cause destruction.
• Heat: Changes in temperature not only directly contributes to destruction of objects and properties but also thermal fluctuations change humidity rate that exacerbate degradation of objects. High temperatures reduce humidity and increase dryness. Low temperatures, i.e., less than freezing points, increases the volume of water which leads to destruction, too. It is fair to say that thermal changes are the most important causes of destructions in buildings and stone statures.
• Air pollution: Air humidity reacts with gases released from burning of different materials that results in production of acidic compounds which causes decay of different objects in the open air. Some of the gas pollutants in the air include sulfur compounds such as sulfur dioxide, hydrogen sulfide, carbon dioxide, and nitrogen oxide. These gases are combined with humidity and produce different acids such as sulfuric acid, carbonic acid and nitric acid. These acids are one of destructive factors. Stains, darkening of lead-based colors and rusting metals are some of the effects of pollutants.
• Light and lighting: Museum objects are vulnerable when exposed to intense lights. Beams of lights contain energies that cause photochemical changes in structures of materials (such as changes in colors and textures of papers and textiles). Additionally, lights heat the surface of materials and the thermal impact increases movement energy of molecules which finally leads to physical destruction. The other impact of lights is creating suitable conditions for chemical actions and reactions as they break down molecular bonds which sets the stage ready for chemical reactions. Lights emitted from natural or artificial sources of lights exert various damages. The intensity of damages depends on wavelength of beams that hit objects. The shorter the wavelength, the higher their energy and consequently the higher the destruction. Compared to others, organic materials are more sensitive to lights. For instance, as the result of lights and lighting, pigments of textiles fade away or papers turn yellow and fragile. Ultraviolet beams leave the most destructive impacts on materials since they have shortwaves. Infrared lights lead to thermal damages which appear directly or contribute to humidity change resulting in indirect damages. Some effects of these damages include bulges in painting boards and cracks in woods.
• Water: Water is another destructive force. Minerals existing in water damages different materials such as woods and metals. Slats existing in water get engaged in chemical reactions with metals that cause decomposition and corrosion of metal objects.

1. Conservative restoration: The main goal of this type of restoration is preservation and maintenance of the properties and monuments. In this restoration method no noticeable changes are made. The amount of intervention existing shapes and conditions of properties is limited to a degree that conditions of restored properties would be completely similar to its status prior to restoration. Therefore, certain limitations need to observed in terms of conservation and restoration methods. Any interventions should be performed in a way that pre-restoration conditions are perpetuated.
2. Anastylosis is a type of restoration by which the architectural style is reconstructed and old architectural elements are recombined. In other words, anastylosis means putting remnants of monuments together and inside the monuments themselves in a way that shapes of their last combinations would have the highest degree of similarity to the primary style of monuments. In case that some parts and elements are missing, new elements should be prepared and mounted in a manner that they should be distinctive from the original parts when one looks at them at the close range.
3. Style cleaning: In this method of restoration, incongruous additions that are not compatible with the original shape of monuments are removed. In some restored properties and monuments some additions have been made that are incongruent and extraneous and/or damaged the authenticity of properties. Therefore, this restorative activity removes these additions and return the authenticity of properties or monuments.
4. Complementary restoration: In this method of restoration, the lost or destroyed parts of monuments or objects are reconstructed. In some cases, the lost parts are big and the integrity of monuments or objects have been compromised. For these cases, the lost parts should be rebuilt. However, some lost parts are very tiny and there is no need for this measure to be taken.
5. Historical restoration: This restoration method aims at reviving the historical life of properties. Therefore, the historical roles of properties determine procedures for their restoration.
6. Fortifying restoration:

The object of this method is preserving strength of skeletons of properties and monuments against forces related to internal performances and/or external agents such as earthquakes. To conduct this type of restoration, one could replace or strengthen some materials and/or replace or strengthen weakened and inappropriate elements and/or fortify the general skeleton of properties.

1. Comprehensive restoration: This method of restoration is more complete than previous methods and it is conducted in light of features of properties and monuments. The most appropriate technical principles and materials are used for this type of restoration whose main objective is preservation of authentic values of properties or monuments.

Materials used in restoration

• Resins: Resins are a group of natural and synthetic organic materials whose physical properties and performance against solvents are similar. Some of the resins used in restoration include Damar, Copal and Mastic.
• Epoxy resins: These materials are produced when epoxies and amino resins react. Epoxy resins are among the most practical pasts used in restoration. As they can mix with different types of powders (such as stone and metal powders), these resins are appropriate for molding.
• Serish (eremurus) paste: This category includes all pastes solved in water (including animal, plant and synthetic pastes). Gelatins, skin eremurus paste and fish eremurus paste are some examples of animal Serish pastes extracted from the collagen existing in connective tissues. These pastes are used when heated.
• Cyanoacrylates: Cyanoacrylates are a family of strong fast-acting adhesives that have high durability.
• Alkaline solutions: Alkaline solutions such as potassium and sodium solutions are mixed with oils and resins to turn them into soapy solutions that are used for cleaning dirty surfaces and removing colors.
• Solvents: Solvents are organic and mineral materials that can solve waxes and fats as resins do. The most notable solvents include alcohols, ketones (such as solvent acetones), ethers, hydrocarbon groups (such as naphthalene and benzene) and halogenated hydrocarbons. They are used for cleaning organic materials such as textiles, removing fat from metals, and/or removing varnished of paintings.
• Polyvinyl acetates: Polymerization of polyvinyl acetates results in compounds that are used for production of adhesives and stabilizers.
• Waxes: Waxes are a group of organic animal or plant compounds that are soft and flexible at low temperatures. Waxes are used for different purposes including repairing paintings and correcting surfaces.
• Acids: They are organic or mineral hydrogen-leaden materials that are used for removing corrosive layers on the surface of metals.
• Salts: Salts are chemical compounds formed by a chemical reaction between a base and an acid. Salts are used for cleaning and deacidification of papers and the like. Slats can lead to decay of objects.

Roles of museums in preservation and protection of ancient objects

As ID cards indicate individual identities, museums and cultural-historical complexes signify national and historical identities of nations whose loss is irrecoverable. Museums and cultural-historical complexes are not used only for visitation, education and pastime rather they are appropriate places for scientific safeguard and protection of unique artistic properties as well as scientific and cultural documents and objects that pass to us from our ancestors and forefathers as a result of good protections in the past. Archeologists make use of some methods to protect these invaluable cultural properties. These methods are defined in scientific principled of conservation whose contribution is protecting properties against destruction, theft and decay. Conservation operations deal with restoration of damaged architectural properties and their reconstruction to revitalize them to their original positions as much as possible. These operations might contribute to prolonging the lifespan of these invaluable properties.

No one can deny the importance of conservation and care for cultural properties. It is not possible to present and introduce these properties at museums and archeological sites. Conservation of cultural properties and objects as well as national-historical properties are undertaken in three ways namely physical conservation, technical conservation and legal conservation.

Physical conservation

Physical conservation is performed to protect old textures of monuments, architectural properties and museum objects. One of the specific measures taken in this field is provision of some facilities at museums and reservoirs to completely protect properties at museums. Some measures for this purpose include making use of double-pane windows, special locks, reliable safes, and appropriate showcases equipped with required safety devices. Additionally, the physical aspects should be taken into consideration for buildings of museums prior to their designs and should be mounted inside museums as integral parts of buildings such as safety systems and equipments and electronic systems inside museums. Trained people should be recruited and deployed outside museums to look after museums and their artifacts. Security teams should be dispatched to take care of cultural-historical sites, too.

1. If all aspects are not taken into account at presentation of museum artifacts and objects, the effects will be detrimental. Presenting museum objects attracts visitors but it might lead to their destruction if appropriate methods of technical conservation are not practices at exhibitions and mounted showcases. This fact is applicable for historical properties since poor technical attention to these properties lead to their degradation or destruction. Therefore, it is necessary and essential to take all technical measures such establishment of research and conservation laboratories, taking care of properties and equipping these centers with advanced machineries in order to protect and preserve museum artifacts and cultural-historical properties, to prevent their destruction of these properties and to conduct restoration on them. Threats such as adverse climatic effects, growth of bugs and plants, inappropriate humidity and temperature and natural disasters such as floods, earthquakes and sever rains are some of these endless factors and loops of this endless chain of decomposition and decay that inevitably occur on the earth. These factors put movable and immovable properties and objects including the old buildings at risks and make them vulnerable. Some materials such as woods, metals, papers, plasters, bricks and colorful materials are more susceptible to these threats. Conservation of these properties need technical information that is related to the science and knowledge of conservation. As a science, conservation is taught as a new independent discipline at universities whereby students acquire knowledge and skills needed for protection of buildings and museum objects at museum halls and reservoirs against humidity, light, dryness, clod and similar factors. Taking different measures for this purpose is called technical conservation. Additionally, scientific methods are taught to carry our appropriate conservation operations for cultural-historical properties by taking into account types of buildings, historical sites and archeological mounds to be used in practice. Conservation of cultural-historical properties is one of the responsibilities of practitioners in this field which has gone international. Misunderstandings about conservation Restoration is one of the ways for preservation of historical properties. One reason for performing restoration is fair transfer of properties to future generations. Some guidelines have been developed since the establishment of conservation and restoration of historical properties as an academic discipline. Some charters have been drafted and some conferences have been organized on conservation and restoration, too. For instance, a definition of restoration was incorporated in the Venice Charter whose main focus was preservation of original materials and authentic documents. However, one of the most important documents on conservation and restoration is the Nara Document on Authenticity that specified important guidelines for restoration of properties and monuments. Preserving authenticity of historical properties is one of the most important issues covered in the Nara Document on Authenticity. Like other countries, some books and dissertations have been written in Iran whose main theme has been authenticity of historical properties. This indicate the sensitivity of the issue of authenticity.Dealing with the issue of authenticity means gaining correct understanding about a cultural property. One important point to be highlighted here is the misunderstandings formed about authenticity that contradict its essential purposes. Misunderstandings allude to lack of correct and perfect information about a historical property. These misunderstandings could be intentional or unintentional. Either cases could lead to severe damages in cultural properties that are sometimes irrecoverable. Misunderstandings has long history in the field of arts and sciences. For instance, lack of precise knowledge about languages might lead to huge mistakes. Orientololgists have occasionally misread a poem or inferred wrong perceptions from biographies or other contents.  Sometimes, names of poets have been read in a wrong manner as the Persian script lacked pronunciation and punctuation marks in the ancient times. These kinds of misunderstanding usually take place about ancient works. Needless to say that restoration is no exception to this general problem. Misunderstandings about restorations have always been with this field since its creation. When a restorer lacks comprehensive understanding about colors used in important historical periods such as the Ilkhanate and the Timurid eras and he essentially does not fathom out the philosophy of colors or differences between original colors and new ones, some misunderstandings will occur in restoration operation. When a restorer embarks on restoration without studying or having knowledge about designs used in the past by old artists and craftsmen, misunderstanding will naturally occur. Two striking examples of such misunderstanding are those related to Kerman Grand Mosque and the tilework of the dome of Sheikh Lotfollah Mosque in Isfahan.

   If a restorer intends to conduct restoration on a historical inscription, he should have sufficient information about original artists or craftsmen, their other works, and principles of inscriptions since engaging in restoration without this information will result in some misunderstandings. Some cases of this problem can be seen in various places as mistakes have taken place about reading inscriptions. Occasionally, restorers and even archeologists have made mistakes in reading and interpreting inscriptions that has led to transfer of false information or wrong restoration. Unfortunately, this problem has been seen in some cases in Iran and this might continue unless serious guidelines are developed for this issue to prevent misunderstandings and wrong restoration operations as they are in perfect contrast with the concept of authenticity and its preservation. Such ignorance might lead to damages in properties. Selecting competent experts for understanding historical properties and recognition of all their aspects is one way to prevent misunderstandings in restoration.

    

   Cultural diversity and its roles in conservation and restoration of cultural and historical properties

   Cultural diversity is an important factor in choosing the conservation and restoration approach. This issue has clearly been dealt with in the Nara Document on Authenticity (adopted in1994). According to this document, judgements about values of cultural properties varies across cultures and even within a culture. Hence, any cultural property should be recognized in its own cultural and social context and authenticity of its values are presented. Respecting the cultural diversity could hinder following predetermined instructions and prescriptions on conservation and restoration and direct approaches and decisions towards understanding and recognizing the culture that owns the intended properties. Gaining correct understanding requires other reviews to get assured about authenticity of properties. Making use of different related sciences, knowing values of properties, monitoring and documenting status of properties in the course of time and paying attention to changes and priorities in terms of values of properties particularly those affected by changes in their environmental, social and contextual conditions, could help restorers gain some requires information and knowledge. However, one should not be incognizant of the fact that it is important to get to a common language in this field to make sure that importance, roles and values particular to any property in every region or culture has correctly been understood by practitioners of conservation and restoration as designers and executors of plans at policy-making levels in upstream organizations and institutions setting conservation approaches at national levels as well as regional and local levels by people as stakeholders to whom the values of properties are partially or completely related since these values are affected by local traditions and cultures. The key for creating such a common language is public awareness raising. Iran is one of the countries whose people have been living peacefully since long time ago irrespective of different religious beliefs, traditions, practices and ethnicities. To deal with various cultural properties scattered across such countries, restorers should have sufficient knowledge and understanding about different related regions and cultures.

    

   Relationship between restorers and cultural-historical properties

   One main issue in defining restoration methods is determining relationships between restorers and cultural-historical properties as well as limits of these relationships. Specified limits can lead to emergence of different representations and results for a specific restoration measure conducted on different properties by various restorers in different countries. Furthermore, different factors such as comprising elements, compositions, structures, value dimensions of cultural or historical properties, limits and environments of properties, and aesthetical issues are instrumental for specifying these limits.

   One factor that can play a decisive role in restorative measures in the audience of properties whose relationship with properties form an important objective in restorative approach. Irrespective of some general principles of restoration and conservation that restores are required to observe and implement them, the effects of the audience on restorers are undeniable. Needless to say that views of the audiences vary across different countries and depend greatly on their understanding and worldview within the cultural context of a society where they have grown. Nowadays, views of the audience about historical and cultural properties do not rely on richness of the cultural heritage of the pertaining country. Rather, different classes of societies can be informed, through presentation and promotion, about values and messages of cultural heritage and their rights concerning them. As this understanding and knowledge gets institutionalized, both restorers and the audience as well as other stakeholders work side by side to carry out conservation of properties. The conservative approach will willy-nilly assume the contrastive or interactive position in its relation to audience’s understanding. The other important topic is desires or views of owners of properties, be an individual, an institution, a nation or a country. Views of audiences about religious and ideological issues can sometimes cause changes in the approach adopted by restorers and restorative actions even in contrast to his own professional and specialized views.

    

1. Another important issue is the importance of legibility in restoration and the amount of visibility of restoration. This topic has extensively been discussed over past years and results of these debates have been incorporated as some articles in restoration charters. Sometimes, restorative interventions can be recognized from a large distance from properties whereas in other occasions observers are required to look at the object within a close range. Making enquiries about factors causing these differences is important. Sometimes, these factors fall within the framework of theoretical principles and foundations of restoration; however, environmental requirements and pressures such as ideological and religious thoughts or local and native cultures and event personal tastes of restorers leave huge impact of it.Two dimensions can be enumerated for legibility in conservation. The first aspect is a specialized one that is manifested in light of criteria and creativities of restorers and determines limits and sizes of restored parts compared to the authentic part. The second dimension is related to the viewer or the audience who is not merely a tourist or a passive observer, rather he is considered an indispensable part of the cycle for understanding heritage and culture and his interaction with properties can play an important role in preservation and survival of properties.Reviews on restorations performed on different cultural and historical properties across the world indicate that their limits and legibility rates are sometimes recognizable but occasionally require careful analysis. In any case, one should not be incognizant of threats of being deceived by apparently clear signals. Similarly, one should not ignore effects of environmental and contextual factors such as cultural, social, religious and political ones. These effects are so strong that sometimes it becomes necessary to violate basic restoration framework for the sake of salvaging a cultural or historical property. Under these circumstances, how can one remain loyal to principles and foundations of conservation and restoration and concurrently gain consent of the audience, owners or stakeholders? The solution lies in considering social and cultural dimension as one effective aspects of the restoration approach since it not only reiterates the important role of audience of properties for adopting restorative approach but also underlines dealing with the issue of awareness raising. Roles of tangible and intangible values

   The other important topic is roles of covert tangible and intangible values in historical properties for determining conservation or restoration approaches and the procedures for determining roles of any value factors. Up to the mid-twentieth century, the main goal of restoration was preservation of physical aspects of properties. However, over recent decades the intangible aspects of cultural properties have been given more attention particularly after compiling and adopting different charters and conventions such as the 1972 Convention concerning the Protection of the World Cultural and Natural Heritage, the Convention for the Safeguarding of the Intangible Cultural Heritage and the Nara Document on Authenticity. As a result, not only are materials and physical aspects of properties are important but also methods and procedures of manufacturing, skills applied, concepts meanings related to properties and beliefs and practices hidden in them are considered as indispensable parts of properties. Accordingly, interventions and restorative and conservative measures in properties are not only concerned with material preservation of properties but also deals with preserving spirits of properties. The shares of these two parts depend on having a complete understanding of properties and their pertaining values as well as their surrounding societies and communities. When an archeological site is concerned whose physical values are not seen greatly by the audience, the difference in these shares become more noticeable as a larger part of the share goes to the spirit of the place or its intangible values and the audience understands necessity of their conservation, protection and transfer to future generations. Therefore, it is not possible to allocate specified and specific shares to spirits or bodies and tangible or intangible dimensions of properties, rather these limits vary across different properties and across different socio-cultural contexts.

   The reason for survival of sites such as Persepolis and Pasargad over more than 2,500 years is not only interests of people to preserve their physical and material aspects, rather it is due to their conceptual and spiritual values among people as they used to practice their religious rites in these locations. The other example was Bam Citadel whose main protectors were people. During the life of this monument before its destruction in an earthquake, people used to hold the most important religious practices and traditions as well as routine traditions within spaces of this monument. Colosseum in Rome and Acropolis in Athens are other monumental examples that allude to important roles played by people in their survival and continuity. According to this line of thought, conservation cannot take place without attachment to properties and this attachment cannot materialize without understanding values and importance of properties.

    

   Economy and conservation of historical and cultural properties

   Effects of economic capacities and limitations on specifying restoration methods should be given attention to. Two issues need to be dealt with here. The first issue is availability or unavailability of financial credits needed for undertaking restoration. It goes without saying that unavailability of financial resources in the modern world can put historical properties at risks of destruction. The striking examples of this situation can be seen in countries such as Afghanistan, Bangladesh and African countries. The second issue is lack or poor technical knowledge. Even if enormous financial resources exist but there is not enough technical expertise, restorative measures will be useless or event destruction and detrimental. Some examples of this terrible situation can be in countries with great financial resources that lack technical expertise. Accordingly, one important measure that must be taken before any conservation and restoration measure is estimating financial resources and technical expertise needed for any projects in the intended country. This estimation can determine limits of roles of each of these factors.

    

   Dealing with past restorations

   The other important issue is correcting restorations conducted in the past and they have been identified to be executed or implemented in a wrong way. Making use of modern knowledge in the field of restoration and conservation of historical properties, one might determine that some methods and conservations applied in the past have been false and destructive. Although theses restorative interventions have been identified as false, they are currently part of the historical property and a part of its existence. Now, the serious question to ponder over is permissibility of interventions in previous restorations and conditions allowing such an action to be undertaken particularly when it is determined that those restorations have been destructive for the properties in terms of both technical and cultural aspects. It is proven that previous restorations have been destructive from both perspectives, that is, inappropriate materials have been used that have put the existence of properties at risk or methods applied have completely damaged values of properties as it happened to Acropolis, cautious interventions in previous restorations will look sensible and justified.

    

   Understanding the emotional environment surrounding historical properties

   When a professional practitioner of conservation and restoration sees a historical property, an image of it is created in his mind and some questions are posed that help creation of a more precise mental picture in his mind such as the following ones:

   What materials have been used in the property?

   To which historical period does the property belong?

   Is the creator of the property known or unknown?

   Finding answers to these questions assist specialists to analyze his mental picture of the property in connection to it and its creator. This mental picture will be completed by understanding factors such as humanitarian perceptions, humanitarian relationships with objects and elements affecting the emotional environment.

   Human emotions depend on his perceptions. Humanitarian perceptions about any issues are related to one’s inputs, data and theories in the course of the life. As one Iranian philosopher has asserted human perceptions are rooted in data, views and past experiences.

   In terms of humanitarian relationships with objects, one should bear in mind that whatever we do contains an emotional aspect. Make use of modern technologies, we adapt ourselves with physical objects and consequently a dynamic relationship and balance is created in our relationships with objects, in addition to relationships that exist among human beings. To understand others’ perceptions and imaginations, we should be able to comprehend these relationships to some extent and put them in a coordinated format or concept.

   Understanding elements affecting the emotional environment is another issue to be taken into consideration for this discussion. Different factors are instrumental for understanding these elements such as social, emotional and economic situations of creators of properties, dates of creation, communities, geographical regions, religions, political and economic conditions, environmental conditions, and temporal and spatial circumstances.

   Understanding structures of properties

   After being created, objects pass through a historical period during which they experience some events that occasionally bring about some damages in the structure of objects and properties. The first step of conservation and restoration measures is understanding structures of objects and definitions related to the structure in order to develop a correct picture of existing conditions of objects. Every structure has its mechanical, physical and chemical characteristics. Analyzing these traits, one can identify structural conditions and situations of objects and partially visualize the emotional environment surrounding objects at their creation time. Structures are composed of elements, members, parts and pieces. Understanding the existing relations among them can leave huge impacts on structural perception of objects and properties. These relations can be fixed, permanent, dynamic, or slowly-changing relations.

   Almost all changes and transformations in objects cause damages. Changes and transformations in objects are inevitable. According to Piaget, paying attention to structures is a method of analyzing observed facts. He believes that this method is of fundamental importance for human sciences. Piaget asserts that every structure possesses three features as follows:

   • Wholeness: It covers internal integrity and structures that organize textures.

   Wholeness means that the system functions as a unit and it is not merely a collection of independent items.

   • Transformation: Transformation means that structures are unstable systems that are constantly changing.
   • Self-regulation: It means that structure maintenance roots in the structure itself rather than its external limits.

   If we focus on understanding structures of objects and take into account aforesaid points, our views would be more perfect in terms of understanding the overall conditions and structures of objects. Hence, paying attention to structures of objects is an intangible, intuitive and thoughtful concern that goes beyond the main visible framework to look at hidden aspects of phenomena. This approach intends to find a solution to explain internal connections and bonds among members and parts. Changes that occasionally lead to transformations in objects, might sometimes cause micro or macro changes and sometimes might lead to destruction and death of objects.