This visualization displays cities on a world map, with circle area encoding each city’s population. A natural Earth projection, rendered via `d3.geoPath`, draws land, country interiors, graticules, and a sphere backdrop in SVG. City coordinates are projected using `d3.geoNaturalEarth1`, and circle radii come from a `d3.scaleSqrt` scale. The map uses world-atlas TopoJSON data, while city populations come from a cleaned CSV of world cities sourced from the UN World Population Prospects 2019.