Fort 't Hemeltje - Houten
Forteneiland 't Hemeltje is the last built fortress of the Nieuwe Hollandse Waterlinie. Nowadays, the Fort 't Hemeltje is home to (breeding) birds and bats and part of the fort serves as office space. There is a walking route around the fort and an exciting spy trail with fun assignments for the children. It is also regularly open to the public, for example during the Open Monument Days.