Mustang Boards - What the heck is there to do in Pittsburgh?

So for Valentine's day I got my gf some Kenny Chesney concert tickets. It's actually a pretty big concert w/ some big names. It's in Pittsburgh which is about 4.5 hours away. We're going to go down a day early, get a hotel and spend two days in Pitt. The onlt thing we could find that sounded good was the Pitt Zoo/Aquarium. They supposedly have a really nice mall as well so I'll let her have a little fun there for awhile.

Does anyone know of anything in downtown area? Or any like well know headquarters in the Pitt area that might have a museum kinda thing.

The concert is at Heinz Field, so we'll be able to check out the stadium before the concert, so we don't really need to plan that part.