Satellite Mapping of Every Building’s Function in Urban China Reveals Deep Built Environment Inequality

Decades of rapid urbanization have profoundly reshaped China’s cities, yet the resulting inequalities in residential built environments remain poorly characterized due to a lack of fine-grained, building-level data. Here, we present the first nationwide functional map of 110 million buildings across 1,094,344 km ² in 109 cities in China, derived from 1-meter resolution multi-modal satellite imagery. Leveraging this unprecedented dataset, we quantify urban inequality across three scales—city tiers, geographic regions, and intra-city areas—using nine indicators spanning urbanization intensity, facility accessibility, and infrastructure sufficiency. Our analysis reveals that: (1) southern cities exhibit the highest access to healthcare, education, and public services but suffer from infrastructure overcrowding; (2) accessibility and amenity diversity decline sharply from top-tier to low-tier cities, while mid-tier cities show the most equitable housing allocation; and (3) later-expanding zones within cities experience more pronounced inequality than early established urban cores. These patterns reflect the legacy of national urban and industrial policies over the past half-century. By linking fine-scale built environment attributes to systematic disparities, this study offers a new lens on urban inequality and provides a fine-scale, actionable framework for equitable urban governance—both within China and in rapidly urbanizing regions globally.