More than 40.000 people, prisoners of war and inmates of concentration camps , like „Neuengamme“ were forced to work at the end of WWII in order to build a shipyard bunker for the production of submarines near Bremen at the banks of the Weser. But the project remained unfinished and no submarine was ever produduced. The bunker weighs 1.200.000 t and  has a length of 426 m, height up to 33 m, the regular thickness of walls and ceiling is 4,5 m, enforced partly to 7 m. Today it serves as memorial.