The Gates of Hell
I don't know a lot about sculpture, but in my humble opinion, Rodin's "The Gates of Hell" is the greatest sculpture in the history of the Universe. Stanford has dozens (hundreds?) of Rodin sculptures (including early maquettes of "The Burghers of Calais"), both inside and outside the Cantor Center for the Visual Arts, as well as scattered around campus. The museum is well worth a visit if you have the chance; it's open late on Thursdays and admission is free, so you really don't have an excuse not to go. The museum is medium-sized, and sort of eclectic, but contains a number of powerful pieces.