Pacifier - I hear ya, I doing research myself right now. I just moved about a year ago and don't know my new area all that well yet. I'm really interested in old military installations, schools/hospitals/institutions and factories. Hopefully I'll get some free time soon and get a chance to find some new stuff to explore. The catacombs would be amazing, do you know if they're open to the general public?
I had to look up Le Hasard Cheratte, wow, I can see why you would want to go there. I can't believe something like that is still standing!
MSD - Thanks for the info. I loved poking around Nike sites when I still lived in Maine, sadly I don't think any were ever built were I live now in Tennessee. There were about 4-5 Nike sites around the base I described in my first post, one in my home town and then appearing at about 10-15 mile intervals in geographical loop around the base. The last time I went into one was about 1998-1999 and at the time, while in terrible shape, you could still get into them pretty easily.
Heres a look at one of them...all though not much is left at this site it appears.
Cold War Relics - Connor Nike
More interesting however is a look at the Weapons storage area at Loring (about half way down the page on the link below starting at photo 29, you can see the vaults, concrete buildings and storage igloos. The rest of the abandoned base is on Loring AFB 1 and 2. Check out the other links along to the top if your interested in other cold war ruins)
Cold War Relics - Loring AFB 2
Oh and the Exide Battery Factory...stunning! I wish I had gone and explored there when I lived closer.
Good stuff folks keep em coming!
Edit: Snuck in on me there Push-Pull, thanks for the link, another great site to poke around. Aside from those sites having great photos they also really assist in finding new places to explore.