Gelsenkirchen is the 25th-most populous city of Germany and the 11th-most populous in the state of North Rhine-Westphalia with 262,528 inhabitants. On the Emscher River, it lies at the centre of the Ruhr area, the largest urban area of Germany, of which it is the fifth-largest city after Dortmund, Essen, Duisburg and Bochum. The Ruhr is located in the Rhine-Ruhr metropolitan region, the second-biggest metropolitan region by GDP in the European Union.