This example demonstrates a hierarchical drilldown of geographic data using the D3.js library, showing districts, projects, and beats in the Palghar region of India. Clicking on a district zooms into the selected area by fetching a new GeoJSON file and redrawing the map with the corresponding sub-regions. The visualization uses `d3.geoMercator` for map projection, `d3.geoPath` for rendering geometries, and `d3.zoom` to handle pan and zoom interactions. A "back" button resets the view to the full district map.