Cologne Bonn Region
The Cologne Bonn Region (German: Region Köln/Bonn) is a metropolitan area in North Rhine-Westphalia (NRW), Germany, covering the cities of Cologne, Bonn and Leverkusen, as well as the districts of Rheinisch-Bergischer Kreis, Oberbergischer Kreis, Rhein-Erft-Kreis and Rhein-Sieg-Kreis. The region covers an area of 3,839 km2 with 3.13 million inhabitants (population density 815/km2).