Fort Hoofddijk (also called Werk aan de Hoofddijk) is part of the New Dutch Waterline. This line runs from Muiden to the Biesbosch and was intended to protect the cities of Amsterdam, The Hague, Rotterdam and Utrecht against enemies from the east by flooding large areas of land.

When Fort Hoofddijk was completed in 1879, it had 12 cannons and was garrisoned by approximately 100 soldiers. The fort was never used in a war, partly due to the development of aircraft that could fly over the line. Five buildings were originally constructed within the fort moat, four of which still remain today: three depots and a large bombproof barracks.

Today, Fort Hoofddijk is located in the middle of the Botanical Gardens and the buildings are used by Utrecht University.