Potsdam is the capital city of the German federal state of Brandenburg. It directly borders the German capital Berlin and is part of the Berlin/Brandenburg Metropolitan Region. It is situated at the river Havel, 24 kilometres (15 miles) southwest of Berlin’s city center. Potsdam has several claims to national and international notability. It was a residence of the Prussian kings and the German Kaiser, until 1918. Around the city there are a series of interconnected lakes and cultural landmarks, in particular the parks and palaces of Sanssouci, the largest World Heritage Site in Germany. The Potsdam Conference, the major post-World War II conference between the victorious Allies, was held at another palace in the area, the Cecilienhof. Babelsberg, in the south-eastern part of Potsdam, was a major film production studio before the war and has enjoyed success as a major center of European film production since the fall of the Berlin Wall. The Filmstudio Babelsberg is the oldest large-scale film studio in the world.