This example shows a world map with circles sized by city population, where each city is positioned by its latitude and longitude. The map uses a stereographic projection and includes graticules, land masses, and country borders. React manages the component state while D3’s `csv` loader fetches city data from a GitHub gist, and `scaleSqrt` maps population values to circle radii. The visualization renders in SVG, with semi-transparent blue circles over a light gray map.