High Quality Content by WIKIPEDIA articles! The Rhine-Ruhr metropolitan region is the largest metropolitan area in Germany with about 10,000,000 inhabitants. It is of polycentric nature and the only megacity in Germany. It covers an area of 7,110 square kilometers and lies entirely within the federal state of North Rhine-Westphalia. The Rhine-Ruhr metropolitan region spreads from the Dortmund-Bochum-Essen-Duisburg (Ruhr Area) megalopolis in the north, to the urban areas of the cities of Mönchengladbach, Düsseldorf (the state capital), Wuppertal, Cologne (the region's largest and Germany's fourth largest city), and Bonn in the south. The location of the Rhine-Ruhr at the heart of the European "blue banana" makes it well connected to other major European cities and metropolitan areas like Amsterdam and the Randstad, the Brussels-Capital Region and Frankfurt/Rhine-Main Region.