Flag of Dortmund, Germany

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 612,065 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 buildings in the inner city centre. The raids, with more than 1,110 aircraft, were the largest for a single target in World War II. Today around 30 % of the city consists of buildings from before World War II. Since the collapse of its century-long steel and coal industries, the region has adapted and shifted to high-technology biomedical technology, micro systems technology, and also services. Other key sectors include retail, leisure and the visitor economy, creative industries, and logistics. Dortmund was classified as a "Node city" in the Innovation Cities Index, ranked among the twelve innovation cities in European Union, and is the most sustainable and digital city in Germany. With its central station and airport, the third-busiest in North Rhine-Westphalia, Dortmund is an important transport junction for the surrounding Ruhr area as well as the Benelux countries, and with the largest canal port in Europe it has a connection to important seaports on the North Sea. Dortmund is home to many cultural and educational institutions. It is the location of the Technical University of Dortmund, Dortmund University of Applied Sciences and Arts, the International School of Management, and other educational, cultural and administrative facilities, with over 49,000 students. It has many museums, such as Museum Ostwall, Museum of Art and Cultural History, and German Football Museum, as well as theatres and music venues like the Konzerthaus or the Opera House of Dortmund. Nearly half the municipal territory consists of waterways, woodland, agriculture, and green spaces with spacious parks such as Westfalenpark and Rombergpark. This stands in a stark contrast with nearly a hundred years of extensive coal mining and steel milling in the past, which created a rich Gründerzeit architectural heritage. Borussia Dortmund is one of the most successful German football clubs.