This example shows an interactive map of urban areas with a click-to-zoom-and-download feature. It displays polygon features from the Natural Earth dataset, and clicking a polygon either zooms to its centroid if the map is zoomed out, or triggers a download of shapefile data from an OpenStreetMap database query. The visualization uses CartoDB.js to create the map and manage layers, with a custom SQL query selecting geometry, area, and centroid coordinates. The code also enables feature interactivity and handles click events to update the map view or initiate a file download.