Although this is mostly terrain, it's not entirely so. Anyways, the general idea is to have one solid version, the outside, and one version with a wall being "see-through". When the player enters the entrance of the outside, his unit is moved to the inside of the building, and center view, viola! This preserves proportions pretty well, so you don't enter a six by six temple and suddenly you're in a 40 x 40 interior, but this means that alot of terrain structions have to be made perfectly proportionate with the interior version, and alot of extra time has to be spend making it look realistic.
good idea, the only real flaw though is that the buildings will be hard to make, and the size of the are you are allowed to move in will be cut down. Also, you'd have to take into consideration the size of the unit compared to the structure.
I like it. It's simple, but that means it's also easy to make, and pretty. It's perfect for what I was planning on making in my Rpg XD