The Constitution Class Starship Enterprise from the show; 26 decks, 2 million+ square feet, 1.2 million blocks (after optimization). Not really a practical deathmatch map, as it's WAY too big and the design was not optimized for DM (e.g., lots of rooms with only one entrance or exit, etc). It's also not set up for single player. Think of it more as a sort of modern art- it exists for it's own sake.
Not a lot of license restrictions- details are in the readme file. Basically, feel free to copy it or modify it, just give credit back where it's due and if you do something really cool, I want to know about it.