Anyway, most of them have been cemented over, but I did find one with a hole in the cement large enough to crawl through. I've never explored them myself, as the guy I was with had no interest.
![Wink :wink:](./images/smilies/icon_wink.gif)
![Rolling Eyes :roll:](./images/smilies/icon_rolleyes.gif)
I can get some more info and solid directions if anyone is interested.