I am always amazed where you can find these dumbs and control centres. We have a few around where I live and one is still very much active. I have seen them here in the UK disguised as everyday companies above ground and something entirely different under ground.
I often knew I was close to one years ago because people would appear from no where and you were either escorted away or at worse driven away and dropped of 20 miles away with a wink and a warning.
Here is an interesting site for URBEX here in the uk, its a group who hunt for and enter these sites, never done it myself though as it is illegal,
http://www.urbexforums.co.uk/