BMAT: a footprint-level building facade material dataset for 73 major cities worldwide

Building facade materials are closely associated with urban microclimates, energy consumption, and carbon emissions, yet existing urban building datasets typically capture only building footprints and heights, leaving semantic material information unavailable at the individual-building level. Here we present BMAT, a footprint-level dataset of dominant visible street-facing facade materials covering 22.09 million buildings across 73 major cities worldwide. BMAT links individual building footprints with facade material labels inferred from over 147 million temporally stamped street-view images collected between 2007 and 2025, where historical imagery is available. We developed an automated inference pipeline based on a fine-tuned vision-language model trained on 39 405 manually annotated samples, achieving an F 1 score of 0.91 against held-out test data. Dataset reliability was further assessed through comparison with 50 823 Overture Maps facade-material records, yielding agreements of 0.72 for the latest BMAT records and 0.79 under a historical matching strategy. BMAT reveals spatially distinct material signatures associated with climate, geography, and regional building traditions. In cities with sufficient repeated imagery, the temporally stamped records further provide exploratory evidence of facade material transitions, including increasing glass facade adoption in selected rapidly urbanizing regions. By linking building geometry with facade-material information, BMAT provides facade material as an important building-attribute input for studies of building energy, embodied carbon, urban microclimates, and hazard risk. The dataset is openly available at https://doi.org/10.6084/m9.figshare.31569370 (Yin, 2026a).