A world map populated with semi-transparent circles representing the populations of cities from a cleaned World Cities dataset. The visualization uses a Natural Earth projection rendered with `d3.geoPath`, layering graticules, land masses, and country borders beneath the points. Circle radii are scaled with `d3.scaleSqrt` based on population, capped at a maximum radius of 15 pixels. The React component fetches TopoJSON world atlas data and CSV city data, then renders the SVG marks with D3 v5.