Fort Ruigenhoek is situated on an uninhabited island covered with old, monumental trees and dense undergrowth, criss-crossed by secret paths. The large defence work on the Ruigenhoek dyke was part of the second ring of fortresses around the city of Utrecht and dates back to 1870. Its purpose was to prevent any approach by the enemy across the Ruigenhoek dyke. The site is occupied by a large square fort with bastions and various outbuildings.