Okay, I check out Litko's "Jim's Product Lab" from time to time, just to see what all that madman has gotten up to lately. Some of the things he creates are just too cool.
This time, I think he's outdone himself. They have a modular building line for sci-fi/modern gaming. While I don't need that kind of thing very much on the projects I am working on these days, he just did up (well, I just noticed for the first time, at any rate) a couple of different sets of stairs to be attached to the outside of some modular towers. I absolutely hate making staircases. Despise it. I make a lot of goofus ladders instead. These may change that.
Naturally, they could be attached to the outside of pretty much anything. or the inside if you were detailing the interior.
Anyway, check here to see it. Scroll down the page a little bit. You'll find them.
Bookmark it - you're going to want to go back again later. I know that I do.