The Rhine-Ruhr metropolitan region (German: Metropolregion Rhein-Ruhr) is the largest metropolitan region in Germany with over 10 million inhabitants. It is of polycentric nature. It covers an area of 7,268 square kilometres (2,806 sq mi) and lies entirely within the federal state of North Rhine-Westphalia. The Rhine-Ruhr metropolitan region spreads from Dortmund-Bochum-Essen-Duisburg (Ruhr Area) in the north, to the urban areas of the cities of Mönchengladbach, Düsseldorf (the state capital), Wuppertal, Leverkusen, 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 the Randstad, the Flemish Diamond and the Frankfurt Rhine Main Region.