During World War 2, this bunker offered protection against British and American air raids. After the war, it remained virtually unused for 60 years. However, after extensive renovation by the International Building Exhibition (IBA Hamburg), it is now an accessible memorial and symbol for renewable energies. In one of the flak gun towers sits the café vju, with its own coffee roastery, where barista courses are held regularly. At a height of 100 feet, the terrace offers a magnificent view over the roofs of Hamburg.