The Spandau Citadel is the oldest remaining structure in Berlin. Berlin is the capital city and one of sixteen states of Germany. The fortress was built from 1559 to 1594. Built on an island created by the meeting of the Havel and the Spree, it was designed to protect the city of Spandau. For the Spandau machine gun see Maschinengewehr 08. For the 1980s New Romantic group see Spandau Ballet. The Citadel has seen a variety of different uses, including an ammunition factory during the Thirty Years' War and the Army Gas Defence Laboratories during WWII. For the Mauritanian Thirty Years' War see Char Bouba war. For the band see The 30 Years War. World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including In recent years it has been used as a museum and a construction school, and is a popular tourist spot.