The place actually takes your breath away. The architecture is amazing. Memorial Hall and the Rotunda of Bancroft hall have some very cool things.... stories of heroes and sacrifices made kept my 15 year old son (who is not very easily impressed if it isn't a video game or have to do with lacrosse) totally silent as he made his way around the rooms. Some of the items around the grounds (for example the figurehead called "Tecumseh") have very cool stories behind them.
We caught a lacrosse game while we were there. The spirit and enthusiasm of the crowd and the team were incredible. I would imagine it is this way for all their sporting events. A fun experience.
Note the visitor center closes (I think at 5 pm) but you can still walk around the grounds. Bring your walking shoes as there is a lot of ground to cover.