In Hellevoetsluis many traces can be seen of Stützpunkt XXVIII (Steunpunt 28) of the Atlantikwall. You can discover it for yourself in the special tour organized by the Defense Works Hellevoetsluis foundation.
Tour is in dutch
Registration is on site or via the website
Times: Every full hour from 11:00 AM. Last tour starts at 4:00 PM
Duration: approx. 1 hour
Start location: Plein Fort Haerlem 1, Hellevoetsluis