Interpreting Spatial Structure, Visual Axes and Borrowed Scenery of Sui–Tang Luoyang Within the Historic Urban Landscape Framework

Sui–Tang Luoyang represents a classic achievement in Chinese capital planning, yet research remains dominated by archaeological and historical–geographical approaches, lacking a unifying theoretical framework. This research addresses this gap by applying the Historic Urban Landscape (HUL) approach to systematically interpret the city’s integration of built form and natural landscape. This research developed a three-dimensional analytical scheme comprising spatial structure, visual axis, and borrowed scenery and implemented it using historical documents, archaeological data, GIS, and cross-validation methods. The results reconstruct the city’s triple spatial structure (Palace City, Imperial City, Outer City) and identify a near-north–south central axis that connects the palace with the Longmen Yique and Mount Mang, forming a dominant view corridor and ritual sequence. Further analysis examines how multi-layered borrowed scenery embodies and articulates the traditional “Harmony of Nature and Humanity” philosophy. This research supports the plausibility of the applicability of HUL to sites with scarce surface remains and provides a transferable framework for the holistic conservation, view-corridor management, and digital reconstruction of historic cities.