Fort Honswijk, originally called Fort Willem II, is one of the most impressive forts of the Nieuwe Hollandse Waterlinie (New Dutch Waterline: a line of defensive works using water throughout the western part of Holland) which is part of this 200-kilometre long UNESCO World heritage Site.

Construction of the tower fortress along the river Lek began in 1841. The tower had three floors with an open artillery battery on the roof. The fort was completed in 1848. In the 1880s, the fort was extensively modified and the top floor was demolished.

Fort Honswijk was used during the mobilisation in World War I. In 1935, the fort was briefly used as a concentration camp. It was the first concentration camp in the Netherlands. Dutch soldiers were based there during the 1939/1940 mobilisation.

Until 2012, the fort was used by the Ministry of Defence. In September 2016, the municipality of Houten became the owner of the fort and it was restored.