Building3D is an urban-scale dataset for building roof modelling from aerial LiDAR point clouds. It consists of more than 160 thousand buildings, covering 16 cities in Estonia about 998 Km^{^2}. Besides mesh models and real-world LiDAR point clouds, it is the first time to release wireframe models. We believe that our Building3D will facilitate future research on urban modelling, mesh simplification, point cloud completion and semantic segmentation etc.