Berlin is the capital of Germany. It is also a city-state, one of the 16 Bundesländer of Germany. From the end of Second World War to the reunification of Germany, Berlin was a divided city, with the eastern part being governed by the surrounding German Democratic Republic (East Germany) and the western part by the Allies (United States, United Kingdom, France). The western part was entirely surrounded by the Berlin wall, built by the Eastern German government. During this period, the capital of the Federal Republic of Germany was moved to Bonn. Today, Berlin has a total area of 892 km² and population of more than 3 million. The mayor is Klaus Wowereit.