The University posts information about gym and athletic facilities, housing and transportation, a campus-wide schedule of activities, and more on their website. Check there for additional information on reunions.
Below are some specific University links:
Princeton University: http://www.princeton.edu/
Princeton Alumni Weekly: http://www.princeton.edu/~paw/
Annual Giving: http://www.princeton.edu/~ag/
Art Museum: http://www.princetonartmuseum.org/
Alumni Records: http://www.princeton.edu/~alco/ALREC.html