This is stupid. But how do you leave the place? I came in through the secret elevator but I can't seem to find it again. This just might be because I seem to be blind to the elevator or something. But running around the map does no good...

If you can't see the elevator, I'd suggest looking around for the sort-of-cunningly dsiguised chain/lever you use to summon it, located immediately next to the elevator itself. I think it's somewhere around the middle-western portion of the area.
No, what I say is not reliable.