Authenticity, Integrity, and Cultural–Ecological Adaptability in Heritage Conservation: A Practical Framework for Historic Urban Areas—A Case Study of Yicheng Ancient City, China

Historic urban areas must adapt to modern cultural ecology for sustainable development while preserving the authenticity and integrity of their cultural heritage. However, this goal is highly challenging due to the complexity of authenticity, integrity, and cultural–ecological adaptability. To promote the dynamic protection and sustainable development of historic urban areas and their cultural heritage, this study aims to systematically define the authenticity, integrity, and cultural–ecological adaptability of historic urban areas and promote their intrinsic unity through the analysis, integration, and deduction of existing research findings and case validation. The empirical research uses Yicheng Ancient City as a case study. The key findings are as follows: (1) Authenticity must preserve the genuineness of daily life, material cultural carriers, and intangible cultural heritage. (2) Integrity should protect all distinctive cultural elements, social functions, material spatial structures, and visual landscapes. (3) Cultural–ecological adaptability must meet the universal demands and local needs of modern cultural ecologies, with particular focus on cultural subjects, functional efficacy, cultural forms, and spatial attributes. (4) All elements of these three concepts are interrelated, and their intrinsic unity can be effectively promoted by integrating their unique characteristics, change features, and mutual compatibility. (5) The authenticity, integrity, and cultural–ecological adaptability of Yicheng Ancient City face five key issues, and six corresponding strategies have been proposed to address them.