Their stadium looked like a state fair until they make it look like a generic pro stadium.
UM and OSU happen to be two of the rare examples of major college football programs with stadiums inspired by classical architecture incorporated into a large venue. (Though Michigan's exterior was inferior to the detail of Notre Dame Stadium.)
Ohio State's expansion and restoration has not preserved that on the outside. There's a sharp contrast from the rotunda to the steel and concrete look of the outer decks. But from the inside they did a good job of retaining proportionality.
Michigan Stadium also just looks like it had two buildings affixed to it on the outside.
I'd be hardpressed to come up with other stadiums as aesthetically pleasing among major football venues.