Bremen [ˈbʀeːmən] is a Hanseatic city-state in northwestern Germany (official name: Stadtgemeinde Bremen / City Municipality of Bremen). It is a port city, situated along the river Weser, about 60 km (37 mi) south from its mouth on the North Sea. Bremen is one of two towns belonging to the state of Bremen (official name: Freie Hansestadt Bremen1 (Free Hanseatic City of Bremen), referring to its membership in the medieval Hanseatic League), the other being Bremerhaven. In 2005, the population of the city was estimated to be 545,983 (the state with the city Bremerhaven have a population of 664,080), while the metropolitan area of Bremen-Oldenburg has a population of more than 2.37 million, so the city Bremen is the number two in North-Germany and the number ten in Germany. Bremen is the oldest city state in the world.