What Hidden Worlds would you like to see?

How about hidden worlds inside a hidden world? I'd love to see the inside of that crystal looking city on Sixam we can see from a distance. I'm assuming that's where all the aliens actually 'live' that spawn to the area our Sims can access.

Or even a fairy world accessed from the 'fairy ring' of mushrooms in Sylvan Glades. It seems like a wasted opportunity to have that mysterious ring and not do anything with it. Just a thought...