Develop a tool to evaluate accessibility in urban areas by modeling street networks as graphs and computing metrics like shortest path distances to key amenities (e.g., schools, hospitals, parks). Use OpenStreetMap (OSM) data to fetch networks, apply graph algorithms for betweenness centrality to identify bottlenecks, and visualize heatmaps of accessibility scores. Implement in Python with OSMnx for network retrieval, NetworkX for analysis, and Folium for interactive maps. Test on multiple cities (e.g., comparing walkability in Cardiff vs. Bristol), evaluate against real-world mobility data, and discuss implications for equitable urban planning. This project integrates GIS with network science for sustainable development.