There are a few lying around Fine Hall in Princeton. One I think is "Five Disks: One Empty" by Alexander Calder.
There's also Marc Pelletier's "Polydodecahedron" which was gifted to JH Conway. http://www.princetonoccasion.org/quarkpark/pages_statements/Conway.html
There's also this big Obelisk in the common room (or did it get moved recently? I seem to remember its relocation when they redid the flooring). I had forgotten what it is actually called and what mathematics it is supposed to represent. Someone should edit this to add in the details.