Dortmund is a city in Germany. It is located in the Bundesland of North Rhine-Westphalia. Its population of 575,944 (2013) makes it the 8th largest city in Germany. Dortmund is the largest city by area and population in the Ruhr Area, an urban area with some 5.1 million (2011) inhabitants which is the largest urban agglomeration in Germany. Dortmund is also a part of the larger Rhine-Ruhr metropolitan region of more than 12 million people.The river Ruhr flows south of the city, and the small river Emscher flows through the municipal area. The Dortmund-Ems Canal also terminates in the Dortmund Port, which is the largest European canal port, and links Dortmund to the North Sea.Dortmund is known as Westphalia's "green metropolis". Nearly half the municipal territory consists of waterways, woodland, agriculture and green spaces with spacious parks such as Westfalenpark and the Rombergpark. This contrasts with nearly a hundred years of extensive coal mining and steel milling within the city limits.HistoryThe first time Dortmund was mentioned in official documents was around 882 as Throtmanni. After it was destroyed by a fire, the Holy Roman Emperor Frederick I (Barbarossa) had the town rebuilt in 1152 and resided there (among other places) for two years. It became an Imperial Free City. Throughout the 13th to 14th centuries, it was the "chief city" of the Rhine, Westphalia, the Netherlands Circle of the Hanseatic League.