Tony D.
Google
Interesting place, you need to book a tour to visit. Guide is very nice and helpful, tour is interesting and the guide is very knowledgeable. You experience both above ground areas and the many kilometres of tunnels below, all hand dug and despite the heavy bombing the underground is still largely intact. Not a lot left of the castle but enough to get an idea of its size and strength. 8 euros a head makes it pretty good value for the 2 hour tour.