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.