Hamburg is a German city-state located in northern Germany. It has an extension of 755 km² and 1,857,727 inhabitants. Hamburg heads a metropolitan area of about 5.3 million people that also occupies parts of the neighboring states of Lower Saxony and Schleswig-Holstein, being the second most populous city in Germany, after Berlin, the third in Central Europe and the seventh in the European Union. The port of Hamburg is the second largest in Europe, only after the port of Rotterdam, and one of the twenty largest in the world. Hamburg is located 290 kilometers northwest of Berlin.