Potsdam is the capital city of the federal state of Brandenburg in Germany. It is situated on the Havel River, southwest of Berlin. It is a part of the Metropolitan area Berlin/Brandenburg. Potsdam is known as the former residence of the Prussian kings until 1918. The city features a series of interconnected lakes and unique cultural landscapes, in particular the parks and palaces of Sanssouci, the largest World Heritage Sites in Germany.