at both universities I'm familiar with, in very different parts of the country, the ground floor is the 200 floor.

You think that's odd? From what I've heard, at my university all of the buildings, except the dorms and older buildings I think, have floor systems based on the football stadium. Apparently all of the 100 floors of the buildings are at the same elevation as the playing field, which is actually sunk down in a small valley. It's a pretty hilly campus, so some of the buildings don't even have a 100 floor. The design school, where all of my classes are, doesn't have one and the 200 level is a basement. The building is so sprawling that there are entrances (to ground outside) on floors 3, 4, 5 and 6.