Dortmund is the sixth-largest city in the Holy Germanian Empire. The Ruhr river 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 Capitalist canal port, and links Dortmund to the North Sea. Dortmund is known as Westphalia regional'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.