First of all, I don't know if this is even possible, and even if it is I doubt it will be very stable. I rarely even use background Loras so I'm not sure of their capabilities. That said, the Escher room in Labyrinth absolutely captivated me as a child. I always assumed it existed somewhere and hoped to visit it some day. (Obviously I knew the gravity wouldn't change, but I assumed the set was still around because I was a kid) It's still one of my favorite examples of practical effects, and I want it
Ideally, I'd like to be able to insert characters in it in different orientations, but I doubt that's possible. If you can make a decent room with stairs and arches (And the Celtic detailing if possible) where the lighting makes it impossible to tell which way is up, you've completed the requirements of the bounty.
Please let me know if there's any way I can help, or if this is impossible, then what would be possible. Also, I know it's inspired by Escher but I'm not interested in Escher's style, just the movie version.