The Rhine-Ruhr area in Germany is in its biggest definition one of the largest metropolitan areas in the world, estimated at close to 13 million people. It spreads from the Ruhr area megalopolis in the north to the urban areas of the cities of Düsseldorf, Wuppertal, and Cologne in the south. As a result of suburban spread, today some say the most northern town of Rhine-Ruhr would be Dülmen, the most eastern Soest, the most southern Bad Honnef , and the most western would be Venlo in the Netherlands. But there are many different definitions of what should belong to a Rhine-Ruhr area, dependent on the definition up to around 130 cities belong to the area.

Cities with more than 100,000 inhabitants

Ruhr area (Westfalian part)

Bochum, Bottrop, Dortmund, Gelsenkirchen, Hagen, Hamm, Herne, Iserlohn, Recklinghausen, Witten

Ruhr area (Rhenish part)

Duisburg, Essen, Moers , Mülheim an der Ruhr, Oberhausen

Bergisches Land

Bergisch-Gladbach, Remscheid, Solingen, Wuppertal

Rhine Valley

Bonn, Cologne, Düsseldorf, Krefeld, Leverkusen, Mönchengladbach, Neuss

Sources

• http://www.megacities.uni-koeln.de