This article, about The Real Royal York Hotel reminded me of stories Curt has told me about the lost lower floors of the Grand Hotel in Scarborough (second pic on left - the street-level entrance is actually in line with the top of the tier you can see from the beach). Apparently there are several levels lower down in the building that are completely sealed off from the hotel proper, and that are never used at all. The Royal York tour is part of a larger site called Infiltration, about ‘urban exploration’. Interesting stuff.

My only experience of this sort of thing is a lot smaller - when I was about 12 or so, my hometown of Bracknell had just acquired it’s first Shopping Mall. There was a lot of not-quite developed space inside the place, which is now filled. In one of the elevator-lobbies there were two (instead of the usual one) doors into stairwells. One is the normal one used to get in and out of the car park, but the other is a fire escape running all the way down the back of the building seperately. Towards the bottom of this, it leads into a space which is now a snooker club and the food court, I believe, and also one day, into a corridor that led over the top of the main entrance into a small gallery behind the mirrored glass of the front doors. I think it’s mostly something else these days, and I doubt I’d try again to get in there.