Fort Henricus is owned by Natuurmonumenten and bears the name of Count Hendrik III of Nassau: one of King Willem-Alexander's ancestors, who is still Lord of Steenbergen. Built in 1626/1627 by order of Prince Maurice, the fort was last put in a state of readiness in 1809, when English troops landed in Zeeland. The sizeable fort was a village in itself and served mainly to protect Steenberg harbour and the inundation sluice. It was located on open water at the time. Hence 'Steenbergen aan Zee' is inscribed on the A4 aqueduct with the harbour canal. Of the thousands of soldiers once stationed at Fort Henricus, many married Steenberg civilian girls. The observation tower at the fort's entrance is a gift from and to the people of Steenbergen, in connection with Mayor Jan Hoogendoorn's farewell in 2012. Climb it and enjoy the view at 't gèèfste plekske aon de Vliet!