Frankfurt (Oder), also known as Frankfurt an der Oder is the fourth-largest city in the German state of Brandenburg after Potsdam, Cottbus and Brandenburg an der Havel. With around 58,000 inhabitants, it is the largest German city on the Oder River, and one of the easternmost cities in Germany. Frankfurt sits on the western bank of the Oder, opposite the Polish town of Słubice, which was a part of Frankfurt until 1945, and called Dammvorstadt until then. The city is located about 80 km east of Berlin, in the south of the historical region Lubusz Land. Within Frankfurt's city limits lies the recreational area Lake Helenesee.