A world map displays cities as semi-transparent, radius-scaled circles proportional to population, using a Natural Earth projection. The visualization, built with React and D3 (v5), renders SVG paths for land, graticules, and sphere outlines via `geoPath`, while circles are projected using `geoNaturalEarth1`. City data comes from a CSV of world cities, and the map’s geographic basemap is provided by the `world-atlas` TopoJSON, processed through `topojson.feature` and `topojson.mesh`.