I don't know why this isn't getting more comments. This is some great work!
I love how you did the stone walls, and everything else is very well done, too.
I'm not sure the ground tiles fit as well as they could with the wall tiles, though. The wall tiles look like an old dungeon, but the ground tiles look more sterile, like a hospital or something. Then again, it gives off a weird atmosphere like this, which, judging by the creepy mouths in the floor, might be what you're going for, heheh.
Cool set, either way!