People say the swiss alps are like an Emmentaler cheer, full of big holes. During a Harley ride I saw the entrance of a Bunker with restaurant inside and the possibility of visits. So I decided to have a look inside, what I found was simply unbelievable!
Build 1939 to 1945 and in use until 1998 and now private own.
More on http://www.festung-furggels.ch