in keeping with everyone else, UF (university of florida) also has this network of underground tunnels. it's pretty normal for steam to be seen rising out of some grates at any time of the day. what i have heard that seems uber cool is that under turlington plaza (many students gather there between classes..it's right across from the carillon bell tower) are an enormous amount of chemistry and physics labs. i have friends who work for the university as light and stereo people, and they have tons of keys that they don't even know what the hell they go to. probably not hidden chemistry lab, but it'd be worth a look, eh?
also, 350 acres is really damn small. UF is the fourth largest in the nation with 2000 acres (at least it was fourth largest when i was accepted; that may have changed).