Bonn is a federal city in the German state of North Rhine-Westphalia, located on the banks of the Rhine. It has a population of over 300,000. About 24 km (15 mi) south-southeast of Cologne, Bonn is in the southernmost part of the Rhine-Ruhr region, Germany's largest metropolitan area and the second biggest metropolitan region by GDP in the European Union, with over 11 million inhabitants. The city served as the capital of West Germany from its formation in 1949 until 1990 and as the capital of reunited Germany from 1990 until 1999 when the seat of government was moved back to Berlin. Bonn is the birthplace of Germany's present day consitution, the Basic Law.