Alumni Hall is quite possibly the coolest building on campus, due mainly to the fact that it is dilapidated, unused, and off-limits. Sadly is unfinished and locked. Alumni Hall will not be completed by the time you graduate.
Alumni Hall would be a BP by now if it weren't for the alumni donations it garners (and the student movement to restore the building). It's actually quite beautiful, and a great place to stage an impromptu concert.
Also it is haunted.
President Amott pledged to raise half the money ($5 million) for Alumni Hall by Founder's Day 2012.