Fort Tienhoven
Fort Tienhoven in the Tienhoven polder was built in 1848-1850 and is part of the New Dutch Waterline. The fort consisted of a defensible guardhouse that was later converted into a bombproof barracks. It served to seal off the Tienhovense Vaart and to guard the adjacent inundation quay, dam sluice and crow's nest lock.
In the period between World War I and World War II, a cast-steel turret casemate for a heavy machine gun was installed to cover the Tienhovense Vaart and Kade.
The fort was returned to nature. Today, bats feel at home there. It is not open to the public, but the surrounding area is regularly refurbished, so the fort is visible from the outside.