This is one of six forts making up the defence line of Den Helder. Fully restored, it now houses an exhibition, a marine aquarium and two restaurants. The guided tour along the underground corridors brings the history of the fort to life. In the blockhouses where the marine aquarium is located, make sure you don't miss the glass tunnel. From the fort, on a clear day, there is a beautiful view of the Razende Bol sandbank, the North Sea and the Island of Texel.