Albert, Martin, and I went to an old WWII bunker in Switzerland. It never saw use, but it was a good set-up if Germany had ever decided to invade. They had 7 machine guns and 3 canons set up looking out over Vorarlberg. It had a range from Bregenz to Feldkirch. We got to see the heavy guns, the bedding areas, the emergency exit, the outside of the bunker (parts were designed to look like summer homes on the outside), the kitchens, hospital, and everything in between.  The bunker stretched probably about 1.5 km and was equipped with multiple 6in thick steel doors. The museum was extremely detailed, they had a huge collection of guns, bullets, helmets, jackets and other equipment from WWII until today. We ended up spending around 3 hours in the bunker, making sure to see every possible room.