Abstract
The study examines how vertical urban form and three-dimensional pedestrian accessibility shape neighbourhood social cohesion among older residents. Survey data from 852 people aged 70 or above across 44 communities in Nanjing are combined with 3D walking distances, gravity-based network construction, social network analysis, and quadratic assignment models. The results show a centre–periphery cohesion structure and indicate that vertical travel barriers matter more than conventional two-dimensional distance measures, with implications for age-friendly planning in high-rise neighbourhoods.