Dortmund (German: [ˈdɔʁtmʊnt] (listen); Westphalian Low German: Düörpm [ˈdyːœɐ̯pm̩]; Latin: Tremonia) is the third-largest city in North Rhine-Westphalia after Cologne and Düsseldorf, and the eighth-largest city of Germany, with a population of 588,250 inhabitants as of 2021. It is the largest city (by area and population) of the Ruhr, Germany's largest urban area with some 5.1 million inhabitants, as well as the largest city of Westphalia. On the Emscher and Ruhr rivers (tributaries of the Rhine), it lies in the Rhine-Ruhr Metropolitan Region and is considered the administrative, commercial, and cultural center 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 industrialization. The city then became one of Germany's most important coal, steel and beer centres. Dortmund consequently 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 center. These bombing raids, with more than 1,110 aircraft, hold the record to a single target in World War II.The region has adapted since the collapse of its century-long steel and coal industries and shifted to high-technology biomedical technology, micro systems technology, and also services. Dortmund was classified as a Node city in the Innovation Cities Index published by 2thinknow, ranked among the twelve innovation cities in European Union and is the most sustainable and digital city in Germany. Other key sectors include retail, leisure and the visitor economy, creative industries, and logistics. With its central station and airport, the third-busiest airport in North Rhine-Westphalia, Dortmund is an important transport junction, especially for the surrounding Ruhr area as well as Europe (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, including the Technical University of Dortmund and Dortmund University of Applied Sciences and Arts, International School of Management and other educational, cultural and administrative facilities with over 49,000 students, many museums, such as Museum Ostwall, Museum of Art and Cultural History, 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. Borussia Dortmund is one of the most successful German football clubs.