Dortmund (German: [ˈdɔʁtmʊnt] ; Westphalian: Düörpm [ˈdyːœɐ̯pm̩]; Latin: Tremonia) is the third-largest city in North Rhine-Westphalia, after Cologne and Düsseldorf, and the ninth-largest city in Germany. With a population of 614,495 inhabitants, it is the largest city (by area and population) of the Ruhr as well as the largest city of Westphalia. It lies on the Emscher and Ruhr rivers (tributaries of the Rhine) in the Rhine-Ruhr Metropolitan Region, the second biggest metropolitan region by GDP in the European Union, and is considered the administrative, commercial, and cultural centre of the eastern Ruhr. Dortmund is the second-largest city in the Low German dialect area, after Hamburg.
Founded around 882, Dortmund became an Imperial Free City. Throughout the 13th to 14th centuries, it was the "chief city" of the Rhine, Westphalia, and the Netherlands Circle of the Hanseatic League. During the Thirty Years' War, the city was destroyed and decreased in significance until the onset of industrialisation. The city then became one of Germany's most important coal, steel, and beer centres; as a consequence, it was one of the most heavily bombed cities in Germany during World War II. The devastating bombing raids of 12 March 1945 destroyed 98% of the buildings in the inner city. Involving more than 1,110 aircraft, the raids were the largest targeting a single city during World War II. Today, around 30% of the city’s buildings date from before the war.