The development of the concept of architectural heritage conservation and its inspiration

Abstract

Over recent decades, heritage conservation has developed in concept and scope. This paper uses a systematic literature review approach to collect charters and documents on heritage conservation issued by UNESCO and ICOMOS, divided into two periods, before 2000 and from 2000 to the present, for analysis from a qualitative perspective. The study results show that the scope of architectural heritage is expanding, and the definition of conservation is changing from individual to holistic conservation and from holistic to sustainable conservation. The focus of conservation has evolved from tangible to intangible attributes. The changing scale of conservation, from object to landscape, incorporates a more comprehensive range of heritage values, and the status of conservation has changed from static to living conservation. This study systematically structures the development of the concept of architectural heritage conservation, providing insight in the international field of architectural heritage conservation and encouraging reflection on the conservation of architectural heritage in historic cities.

1 Introduction

UNESCO (United Nations Educational, Scientific and Cultural Organisation) and ICOMOS (International Council on Monuments and Sites) have been exploring and guiding the conservation of the environment, cities, and buildings since their establishment. They have accumulated a wealth of experience. Since the start of this century, experts from the UNESCO World Heritage Committee have thought it was time to shift the process of architectural heritage conservation. They are gradually becoming aware of the objective reality of urban development, that historic cities are facing conflict between conservation and development and that architectural heritage conservation can no longer focus only on the conservation of buildings. The conflict between sustainable development and heritage conservation is a balancing act between preserving the importance of heritage and allowing sustainable development (Fouseki and Cassar 2014; Adams et al. 2014; Arumägi and Kalamees 2014; Broström et al. 2014; Eriksson et al. 2014; Fabbri 2013). Thus, the Recommendation on the Historic Urban Landscape was created.

In 2011, UNESCO adopted the Recommendation on the Historic Urban Landscape, which addresses the negative impact of urban development on heritage conservation and the contradictions and problems between architectural heritage conservation and modern urban development. It argues that rigid and dogmatic conservation strategies need to be adapted to a city’s social context and economic environment (UNESCO 2011). History and development should not be opposites but rather mutually beneficial (Najd et al. 2015). The historic urban landscape is an approach that incorporates both the historical environment and contemporary space into the conceptual scope (Yang, Brumana and Previtali 2019). The conservation of architectural heritage in urban spaces is not only about preserving the historical buildings of the past but also about uniting stakeholder groups, identifying architectural heritage, gaining a collective cultural identity, finding a sense of place and civic pride for residents, allowing everyone to appreciate the cultural values of the city today, and creating a cultural identity for future urban planning through this process (Cauchi-Santoro 2016).

Before 2000, the definition and scope of architectural heritage conservation were based on a series of ICOMOS charters, resolutions, and declarations surrounding The Venice Charter in 1964. In 1987, the definition and scope of architectural heritage conservation in The Washington Charter were gradually extended beyond protecting the building itself. The charter provided a new concept of architectural heritage conservation, defining the concept of architectural heritage and its historic location and larger historic urban areas. In addition, it defined the notion of holistic conservation.

In 2005, the historic landscape of cities was first introduced in the Vienna Memorandum adopted by UNESCO (UNESCO 2005), stimulating a new way of thinking. In 2011, the term was formally introduced in the Recommendation on the Historic Urban Landscape (UNESCO 2011), which pointed out that change is considered part of the urban tradition and was widely discussed. Reviewing and summarising the evolution of architectural heritage conservation reveal that the definition and scope of architectural heritage conservation have changed from The Venice Charter to the Recommendation on the Historic Urban Landscape.

How has the concept of architectural heritage conservation developed from the Athens Charter for the Restoration of Historic Monuments to the present? How has the scope of architectural heritage conservation changed accordingly?

2 Research aim

This study aims to analyse the development of architectural heritage conservation and discuss changes in the concept of architectural heritage conservation by analysing the charters and documents on architectural heritage conservation issued over the years by ICOMOS and UNESCO to gain a deeper understanding of the concept of architectural heritage conservation. On this basis, it reconceptualises and clarifies the systematic nature of the concept of architectural heritage conservation, reveals the development of architectural heritage conservation, and identifies its implications for the conservation of architectural heritage in historic cities. Architectural heritage conservation is not static and changes with time and the development of society. Therefore, systematically examining the development of the concept of architectural heritage has far-reaching guiding significance for the definition of architectural heritage, the determination of its scope, and the stimulation of its value.

This study adopts a systematic literature review approach to collect charters and documents on architectural heritage conservation issued by UNESCO and ICOMOS for analysis from a qualitative perspective and compiles statistics for two periods: before 2000 and from 2000 to the present. The full texts of the charters and documents on architectural heritage conservation were read so that views adopted in the concept of heritage and leading views on the scope of heritage could be extracted and listed and the four aspects of definition, focus, scale, and status of architectural heritage conservation could be analysed. Finally, the study elaborates on the inspiration for architectural heritage conservation in historic cities, leading to reflection on the conservation of architectural heritage.

3 Development of the concept of architectural heritage conservation

3.1 Development of the definition of architectural heritage conservation

In 1931, the Athens Charter for the Restoration of Historic Monuments was established. It proposed the need to study the suitability of decorative flowers and trees for certain monuments or groups of monuments, to eliminate all forms of advertising and the erection of unpleasant electric poles in the vicinity of monuments of artistic and historical value, to prohibit the construction of noisy factories and towering pillars, and to better protect the monuments themselves (ICOMOS 1931). The Athens Charter for the Restoration of Historic Monuments was the first official document on the protection of cultural heritage to be accepted at the international governmental level. In a sense, it was the beginning of the formation of an international consensus.

Subsequently, in 1964, The Venice Charter was formed. It argues that monuments cannot be separated from the history they represent and the environment in which they were created (ICOMOS 1964). Historic monuments include the monuments themselves and their historical environment. The charter was an essential moment in the cultural debate, as it expanded the definition of historic monuments, emphasised the protection of the environment in which these monuments are located, and accelerated the expansion of conservation standards from individual buildings and groups of buildings to buildings and the environments with unique civilisations that they contain (Jokilehto 2013; Goetcheus and Mitchell 2014; Ahmad 2006). Based on the Athens Charter for the Restoration of Historic Monuments, it reaffirmed the scope and significance of heritage conservation. More important, it expanded the definition of heritage conservation and provided a complete definition of architectural heritage conservation. However, it is not perfect, as it focuses on single historic site conservation, ignoring the problem of the city, and therefore the macro-level.

In the stage, the focus was on historical heritage conservation of a single substantial space, and the scope of conservation attention was narrowed. However, the scope of monument conservation has changed as the understanding of conservation value has changed and expanded. The object of conservation has gradually expanded from a single historical building to the level of historical areas. The Athens Charter for the Restoration of Historic Monuments formed a preliminary understanding of the environment surrounding historical buildings.

The concept of architectural heritage conservation has been widely promoted and accepted through the definition of the historic urban landscape in the Recommendation on the Historic Urban Landscape, which expanded the scope of architectural heritage. Moreover, the scope change in architectural heritage conservation documents triggered changes in programmatic documents for architectural heritage conservation. In terms of connotation, some critical changes occurred in architectural heritage conservation documents after 2000.

3.1.1 Quantity and proportion

The charters adopted by the general assembly of ICOMOS as well as resolutions and declarations issued every two years are consensus documents for the heritage conservation academic community and influence the conservation practices of governments. Since its establishment in 1965, ICOMOS has issued or endorsed 49 documents. Among them, 19 charters were adopted by the general assembly of ICOMOS, 17 resolutions and declarations, 7 charters were adopted by ICOMOS national committees, and 6 other international standards were issued. There are 45 documents on architectural heritage conservation (Table 1).

Table 1 Architectural heritage conservation document statistics of ICOMOS

Regarding the number and type of documents the period before 2000 was a significant era of development. There were 26 documents related to architectural heritage conservation, accounting for 96.30% of all documents; from 2000 to the present, there were 19 documents, accounting for 86.36% of all documents. Most of these documents were promulgated between 1980 and 1990, with 11 documents related to architectural heritage, more than in any previous period.

UNESCO’s conventions, recommendations and declarations are the programmatic and guiding documents for architectural heritage conservation. Since its establishment in 1946, UNESCO has issued 12 documents related to architectural heritage conservation, accounting for 13.58% of the total number of documents (Table 2).

Table 2 Architectural heritage conservation document statistics of UNESCO

The number of UNESCO documents on architectural heritage was significantly higher after 2000 than before. There were 2 conventions, accounting for 25%. The Convention for the Safeguarding of the Intangible Cultural Heritage in 2003 and the Convention on the Protection and Promotion of the Diversity of Cultural Expressions in 2005 emphasise the importance of culture for social cohesion, not only protecting and safeguarding people but also enhancing the diversity of cultural expression. There was 1 recommendation, the Recommendation on the Historic Urban Landscape issued in 2011, accounting for 12.5%, and 2 declarations, accounting for 28.57%.

3.1.2 Cognition of heritage setting

The ‘setting’ of heritage is originally derived from the concept of the surrounding environment or natural environment. In the Charter of Athens (CIAM 1933) and the Recommendation Concerning the Safeguarding of Beauty and Character of Landscapes and Sites, the word ‘surrounding’ refers to the natural environment (UNESCO 1962). The first use of the term ‘setting’ was in The Venice Charter for heritage conservation. The historical environment at this stage referred mainly to artificial physical constructions and ancient remains (ICOMOS 1964). Along with developing the understanding of heritage value, many charters provided different definitions of the ‘setting’ of heritage, resulting in different connotations of ‘environment’. The Recommendation Concerning the Safeguarding and Contemporary Role of Historic Areas clarified that ‘Architecture adapts harmoniously to the spatial organisation and setting of the groups of historic buildings’ (UNESCO 1976). The Washington Charter paid attention to the relationship between the neighbourhood and the surrounding environment. ‘Setting’ is the surrounding environment, both natural and artificial (ICOMOS 1987). In The Burra Charter, ‘setting’ refers to the area around a heritage site, including the scope of vision (Australia ICOMOS 1999). The European Landscape Convention proposes that all landscapes are important and that landscape is a cultural concept (Council of Europe 2000). The Xi’an Declaration on the Conservation of the Setting of Heritage Structures, Sites and Areas elaborates on the ‘setting’ of heritage from the perspective of heritage integrity. The environment includes the immediate environment of heritage and the extended surrounding environment that affects its importance and uniqueness, or the components of its importance and uniqueness. It reflects the connotation of the relevance of heritage, and the continuity of the heritage environment from past to present, emphasising the integrity of heritage (ICOMOS 2005; Patiwael, Groote and Vanclay 2019; Jokilehto 2007).

Therefore, we believe that the ‘heritage environment’ is the relevant setting of heritage and should incorporate the connotation of ‘setting’ from the Xi’an Declaration on the Conservation of the Setting of Heritage Structures, Sites and Areas. It covers the internal and external, individual and mutual, historical and present-day, objective and multifaceted interrelationships of heritage, and emphasises the outstanding contribution to heritage values.

3.2 Development of the focus of architectural heritage conservation

A major underlying force in the evolution of heritage conservation is the shift in focus from the physical structure of heritage itself to the meaning that heritage conveys. The Burra Charter states that cultural significance is embodied in the place itself, its fabric, settings, use, association, meaning, recording, related places, and related objects (Australia ICOMOS 2013). Such significance is an essential aspect of an object assigned by an individual or society. Meaning is why heritage is valued and why it is preserved (Bracker and Richmond 2009; Pye 2001; Olukoya 2021).

The UNESCO Universal Declaration on Cultural Diversity in 2001, the Convention for the Safeguarding of the Intangible Cultural Heritage in 2003, and the Convention on the Protection and Promotion of the Diversity of Cultural Expressions in 2005 regarded the conservation of architectural heritage as an essential part of cultural diversity and emphasise the importance of culture. Culture has become the conceptual basis for the conservation of architectural heritage. Architectural heritage is the concept not only of material heritage but also of culture. The Convention for the Safeguarding of the Intangible Cultural Heritage in 2003 recognised that intangible and material cultural heritage are interdependent. Such heritage is also a crucible of cultural diversity and a guarantor of sustainable development. The Xi’an Declaration on the Conservation of the Setting of Heritage Structures, Sites and Areas in 2005 further extended the scope of the conservation and continuation of architectural heritage to relevant intangible heritage (Gregory 2008; De Silva 2023). The Recommendation on the Historic Urban Landscape in 2011 recognised the correlation between heritage and environmental background. It provided a new perspective and methodology for architectural heritage conservation. This shift from focusing on tangible attributes to including intangible attributes is an essential aspect of the evolution of conservation concepts.

3.3 Development of the scale of architectural heritage conservation

In terms of the content of the documents, the architectural heritage conservation documents show a trend of systematisation and development. Starting with The Venice Charter in 1964, the scale of conservation has been constantly updated with the development of the times.

In 1976, UNESCO adopted the Recommendation Concerning the Safeguarding and Contemporary Role of Historic Areas, which stated that new development can destroy the environment and features of historic areas and that architects and city planners should exercise care to ensure that monuments and views of historic areas are not destroyed and that historic areas can be integrated harmoniously into contemporary life as a whole (UNESCO 1976). Moreover, it emphasised that historic areas can be integrated into contemporary life as an integral part of the city as a whole. In 1987, The Washington Charter was formed. It points out that all cities and communities, whether developed gradually over a long period or intentionally created, contain the history of all sorts of social manifestations, and their natural and artificial environments (ICOMOS 1987). These entities embody the value of traditional urban culture. Building on the Recommendation Concerning the Safeguarding and Contemporary Role of Historic Areas, it expanded the concept and content of the conservation of architectural heritage. It established the concepts of historical sites and larger historic urban areas. Compared to The Washington Charter, the recommendation placed more emphasis on buildings and the relationship between green space and open space, the relation between towns and urban areas and the surroundings, updating the evolution of history and the relationship between historic areas and urban development. In 2000, the European Landscape Convention recognised that all landscapes should be viewed as valuable and vital in the healthy development of individuals and societies (Council of Europe 2000 2000). The convention emphasised that all landscapes have significance and provide a sense of identity for urban development (Priore 2001). In 2005, ICOMOS issued the Xi’an Declaration on the Conservation of the Setting of Heritage Structures, Sites and Areas. It pointed out that the concept of heritage, in addition to the protection of the material body, should include the relationship between that body and nature, intangible heritage, the sociocultural environment, and the relationship with the environment itself as indispensable parts of heritage value (ICOMOS 2005). It allowed the architectural heritage to be protected together with the environment, emphasising the cultural importance of the environment (Xie, Gu and Zhang 2020). It systematically declared that the relevant setting is an indispensable component of the integrity of the heritage value, not an optional appendage. In 2011, the Recommendation on the Historic Urban Landscape defined the concept of a historic urban landscape as an urban area generated by the historical accumulation of cultural and natural values and attributes. It extended beyond the concept of a ‘historic centre’ or ‘whole’ to include a broader urban background and its geographical environment (UNESCO 2011). The Recommendation on the Historic Urban Landscape held that architectural heritage conservation is systematic and sustainable, rather than static conservation for a specific type of material heritage. It emphasised the inherent relevance of various heritage elements. It was a living exploration of architectural heritage conservation in the field of urban planning, intending to maintain a balance between architectural heritage and contemporary needs. Its purpose was to integrate the whole development of history and culture into each part and area of conservation, ensure the inheritance and sustainable development of history and culture, treat architectural heritage and urban space as a system, establish identity from the individual to the whole, and strengthen the spirit of place. In 2014, the Florence Declaration elaborated landscape as a rich concept encompassing heritage as a synthesis of nature and culture (ICOMOS 2014). Therefore, landscape is increasingly becoming a paradigm for harmonious development, offering new ideas for integrating economic, social, and environmental development.

With the development of the times, heritage conservation documents have elaborated on the heritage concept of historic buildings and monuments and included concepts of historic towns, historic gardens, and historic areas. The relationship with the city, from architectural objects to landscapes, is increasingly important.

3.4 Development of architectural heritage conservation

As the concept of architectural heritage conservation has developed, it has put forwards new conservation notions and values.

3.4.1 Highlight of local value

The Venice Charter for the first time explicitly introduced authenticity to cultural heritage to enable cultural heritage to be inherited with complete authenticity. The Venice Charter stressed the conservation of cultural heritage in its original state and the valid contributions of all periods (ICOMOS 1964). It fully expressed the original concept of the connotations of cultural heritage conservation, that is, the initial state and the environment at that time. To highlight the local value of heritage is to respect its authenticity.

In 1994, the Nara Document on Authenticity proposed the principle of the local value of heritage. Heritage assets must be considered and evaluated in the cultural context to which they belong in order to respect all cultures (ICOMOS 1994); thus, recognition of heritage value must be related to local social life. At the same time, respect for the diversity of culture and heritage is necessary to determine the authenticity (ICOMOS 1994) of architectural culture. The diversity value of heritage comes from its locality as historic remains in a specific space, and the local value of architectural heritage comes from the value of cultural diversity. Then, Australia issued The Burra Charter based on the concepts of fabric and place, distinction and connection (Australia ICOMOS 1999), repurposing the Athens Charter for the Restoration of Historic Monuments in terms of the basic orientation towards historical building protection. From the perspective of a single individual, space as a whole, highlights the emphasis on heritage conservation in the spirit of the integrity of cultural significance. In 2005, the Xi’an Declaration on the Conservation of the Setting of Heritage Structures, Sites and Areas also emphasised the importance and uniqueness of heritage are in the social, spiritual, historical, artistic and aesthetic, natural, scientific, or other cultural value (ICOMOS 2005). Additionally, the spirit of heritage is related to the physical, visual, and cultural aspects of the vital link to the background environment (ICOMOS 2005). Heritage is a specific and unique cultural form, and the recognition of its value should first be based on respect for its locality, which is a dialectical value principle in the sense of authenticity.

3.4.2 Study of living conservation

The Venice Charter defined the concept of architectural heritage as including not only a single building but also a unique civilisation and the development of a meaningful or historical witness of an urban or rural setting (ICOMOS 1964). It began to pay attention to the meaning of development, and the conservation of architectural heritage was not confined to static conservation. The European Charter of the Architectural Heritage systematically discussed the social significance of the conservation of architectural heritage and proposed the concept of holistic conservation (Council of Europe 1975). The practical significance of protecting architectural heritage was clarified, and the vital role of architectural heritage in providing living environmental quality, maintaining social harmony and balance, and supporting culture and education was recognised. The charter also pointed out that the future of architectural heritage depends to a large extent on its integration into people’s daily living environment and its importance in regional and town planning and development (Živaljević-Luxor, Kurtović Folić and Mitković 2020). The Washington Charter put forwards the relationship between the conservation of historic cities, urban areas, and urban development. The conservation of historic cities should be an integral part of social and economic development policy (ICOMOS 1987). The charter contained the most comprehensive definition to date of urban conservation. The conservation of historic towns and cities means that various steps are necessary for their protection, preservation, and restoration as well as their development and harmonious adaptation to modern life (ICOMOS 1987). It suggested that architectural heritage conservation not only involves museum-based protection but also must adapt to modern life. The modern concept of conservation is based on the conservation of historical blocks and urban context. The conservation of architectural heritage extends to the preservation of cultural and regional characteristics, which involves a shift from simple protection to the updating and development of the city. The Vienna Memorandum considered the natural and ecological environment of any buildings or structures. It pointed out that architectural heritage is the core of the challenges and development trend of coordinated interaction (UNESCO 2005) and put forwards coordinated conservation as a new way of thinking about architecture, sustainable urban development and landscape, and careful consideration of urban heritage conservation, urban modernisation and social development. The Xi’an Declaration on the Conservation of the Setting of Heritage Structures, Sites and Areas pointed out that the environment creates and forms the environmental space as well as the current dynamic cultural, social, and economic background (ICOMOS 2005). It regarded heritage as a dynamic and composite whole rather than a static and independent state and recognised the impact of environmental dynamics on heritage value. The Recommendation on the Historic Urban Landscape pointed out that positive conservation of urban heritage and its sustainable management is essential for development (UNESCO 2011). These changes are beginning to be regarded as part of the tradition, and conservation has become sustainable based on the balance between urban growth and quality of life (Bandarin and Van Oers 2012). A strategy in the context of broader thinking about urban historic landscape conservation, emphasises the dynamic, continuous, living and holistic understanding of this way of thinking. While the dynamic nature of this strategy should be recognised, the sustainable use of urban space should be improved and the architectural heritage conservation goal combined with urban development. The results of living conservation can achieve economically sustainable, socially harmonious and environmentally friendly development (Cooper 2001).

From The Venice Charter to the Recommendation on the Historic Urban Landscape, the status of architectural heritage conservation has been changing. This change involves the vision of how people view the relationship between architectural heritage and the contemporary world, from the initial emphasis on the harmony between them to the gradual and profound recognition that architectural heritage is an important resource for contemporary development. Architectural heritage is moving from static to living conservation, from mere conservation to focusing on the development of the era of generating architectural culture.

4 Inspiration for architectural heritage conservation in a historical city

The Recommendation on the Historic Urban Landscape in 2011, which proposed that architectural heritage conservation should be viewed systematically, is a conservation document with historical significance. Over time, the definition of architectural heritage conservation has gradually developed, from representative buildings in human history to important relics of human cultural exchanges to important assets closely related to urban development. At present, the contradiction between architectural heritage protection and urban development in historical cities is becoming increasingly severe. Therefore, it a breakthrough from the traditional protection mode is urgently needed. Undoubtedly, the development of the scope of architectural heritage conservation can provide inspiration.

4.1 Reaching a consensus on the holistic value of architectural heritage

With the development of the definition, focus, scale, and status of architectural heritage conservation, the emphasis is increasingly on the holistic value of architectural heritage, from a single building to a focus on the surrounding environment and urban development. The concept of architectural assets has moved from a single building to a focus on the surrounding environment and urban development, with increasing emphasis on the overall value of architectural heritage. Understanding the authenticity of architectural heritage is first based on recognising the overall scenario in which it is situated. This totality goes far beyond heritage as an object. We must realise that architectural heritage, as a form of cultural heritage, naturally contains inherent temporality and spatiality in its historical generation. We must pay attention to the relationship between architectural heritage as a specific object and its natural, social and cultural contributions. Thus, the value of heritage cannot be separated from the social framework in which it is historically generated.

4.2 Attaching importance to the investigation and utilisation of architectural heritage

Different cities have different cultural forms and physical and geographical conditions, so they will approach the preservation of their heritage culture and achievements in different and diverse ways. Therefore, it is essential to carry out an extensive survey and assessment of architectural heritage and understand the distribution of heritage resources in each city, as this is an important measure to ensure the most efficient conservation of heritage achievements. From focusing on individual heritage to the conservation of the city as a whole, the protection of architectural heritage will be the result. Focusing on the interactions of architectural heritage will enable the conservation of heritage to be closely integrated into the development strategy, thus making the conservation of architectural heritage systematic and strategic. The use of heritage based on resource investigation adapts to the material and spiritual needs of modern society, enhances the cultural characteristics and vitality of the city, and at the same time promotes sustainable urban development.

4.3 Exploring the holistic conservation of specific areas

As the product of a specific environment, architectural heritage is a cultural form that cannot stay in isolation for conservation; rather, conservation should be based on more extensive context and planning, as such heritage is inseparable from people’s lives. Space is a human creation, dependent on the existence of people and interaction with them, and the conservation of architectural heritage space is the conservation of architectural heritage as a whole. Spatial analysis can lead to a more scientific recognition and better understanding of the nature of architectural heritage in urban space. It also shows that architecture is the science of art and the geometric forms of architecture (Alnaim 2020). Based on the above theory, architectural heritage space can be analysed and studied from a holistic perspective to grasp the overall characteristics of the spatial system. Second, the integration of architectural heritage should be studied dynamically to identify the essence and causes. Finally, the focus should be on the stages of the spatial development of architectural heritage and its interaction with the city.

5 Findings and discussion

In recent decades, the definition of architectural heritage has expanded from the building itself to the site and from the surroundings to the urban background. It has become the direct cause of broadening values that are considered to have cultural significance, and these new values are now part of all decisions taken to conserve architectural heritage (De la Torre 2013). This evolution has moved from the traditional view of conservation, protecting the material fabric of objects that are assigned monument status, to the current view, which aims to protect the values represented by architectural heritage ranging from objects to landscapes. This shift is depicted in Table 3, which compares the definition and scales of the traditional conservation paradigm to the definition and scales of the current conservation paradigm.

Table 3 Evolution from traditional conservation to current conservation

This study outlines recent developments in the definition and scope of heritage and provides an overview of them from the perspective of sustainable development. It aims to provoke reflection on the conservation of architectural heritage in historic cities to adapt to the needs of sustainable development and contribute to heritage conservation. The scope of what constitutes heritage is expanding, shifting from the physical to the landscape and the environment, and the definition of heritage is also expanding. Additionally, heritage studies are becoming more tolerant of change. Therefore, the current paradigm of conservation of architectural heritage is a balance between conservation and development.

6 Conclusion

The scope of conservation of architectural heritage has expanded from historic areas to historical urban areas and their surrounding areas, emphasising the holistic conservation of the surrounding area, historical relics, and historic urban areas. The Washington Charter emphasised the conservation of historic districts, summarised experiences and practices in many countries, and clarified historical area conservation content because the historical block initially formed a relatively complete protection research system. Nevertheless, with many urban renewal practices and contradictory architectural heritage conservation practices deepening the frequency and various social problems of architectural heritage, the Recommendation on the Historic Urban Landscape paid more attention to architectural heritage conservation to coordinate with the development of the surrounding area and to realise the sustainable conservation of architectural heritage and development.

The analysis of the architectural heritage conservation documents promulgated by ICOMOS and UNESCO reveals that the definition of architectural heritage conservation is no longer limited to material objects. Rather, architectural heritage has been conceptualised in terms of conservation connotations, objects, and scope. In this context, the definition of architectural heritage conservation has changed from The Washington Charter to the Recommendation on the Historic Urban Landscape.

This study focuses on the historical lineage and conceptual development of architectural heritage conservation. However, it is not a purely theoretical study; rather, it starts from the theory and identifies its implications for the conservation of architectural heritage in historical cities. The in-depth analysis of the development of the concept of architectural heritage can be helpful for the planning and design of urban renewal, coordination between urban development and conservation, and the practice of architectural heritage conservation in urban design and urban management. Additionally, this study can add to the applicability of architectural heritage conservation in urban development, thus contributing to developing architectural heritage conservation principles applicable to cities. As articulated by UNESCO, architectural heritage conservation is a form of urban conservation that does not replace established doctrines and conservation methods but integrates environmental protection, policy development, and heritage conservation practices. However, architectural heritage conservation in cities involves all levels of urban history and is a comprehensive and extensive system that requires multidisciplinary participation. This study briefly reviews UNESCO and ICOMOS documents and conferences. It analyses the conceptual development of architectural heritage conservation to provide architectural design, urban conservation, and urban planning practitioners with an understanding of the historical context of architectural heritage conservation, promoting cross-collaboration in urban architectural heritage conservation research and enhancing the importance of architectural heritage conservation in more fields.

With the deepening and updating of understanding and concepts, the value of architectural heritage and the concepts of heritage conservation are no longer limited to the building but have expanded to include the historical and cultural framework, comprehensive values and roles, and sustainability. Architectural heritage conservation has developed into a specialised science involving architecture, planning, history, archaeology, and sociology. Therefore, the challenges are to learn from the current conceptual development of architectural heritage conservation in historical cities, to explore and develop conservation theories and methods in line with the characteristics of historical cities and architectural heritage, and to balance the relationship between conservation and development.