We all know the first . But if there's anything that could compete with it, it would have to be what these guys do:

http://www.actionsquad.org

I especially like their explorations of things like old drain systems and steam tunnels. There's something deeply appealing about "urban exploration" to my psyche. The hidden complexity all around us that most people never even realize exists in the first place; going where "they" don't want you to go; seeing what you're not supposed to see; finding the elegant ways to get in and out without anyone knowing you were there...

I can't quite explain it, but there's a strange sort of synchronicity between urban exploration and reversing.

Howdy,

I have always been involved in urban exploration.
Sometimes not so urban but involved none the less.

Mine is a fascination with buildings that have been
surrounded in some kind of secrecy.

State hospitals are probably the best.

For those of you who are not from the USA, State hospitals have
quite a history here. As man tried to understand mental illness, many people were warehoused in the these facilities because society did not know what to do with them. It was not until the late 80's, early 90's when these facilities were "emptied" so to speak. The buildings were left empty for decades before they were either torn down or re-habbed.

I could go on forever about this topic.
If you want more, let me know .

Woodmann

My first hobby is "boinking" around with the fairer sex. Reading books comes a close second. Cracking is somewhere 13th on that list. Woody unca, I'd rather be exploring the secrets of what lies above the sweaty thighs than urban pipes. Heh!

Have Phun

If you still consider that a "secret", I'd say you haven't been very successful in your primary hobby, and might want to consider moving it down on your list a bit ...

what lies above the sweaty thighs is no secret, but you may find out its hidden biological, bacteriologic and virological surprises the hard way, if you are not careful.

Always wear head protection in your discovery adventures. . .

Ha, ha, ha. Haven't you heard..."each mountain, each cave is unique...and worth exploring"