Directly across the street from the Monadnock is the Chicago Federal Center, designed by famed architect Mies van der Rohe. His "less is more" Bauhaus style is on full display here -- the two tall buildings that make up the center are big, black hulks of glass and steel. Unlike other plazas in the city that have fountains, grass, and places to sit, the plaza at the Federal Center is cold, uninviting, and the minimal seating it does have is a couple slabs of marble, and combined with the one-story post office, everything feels very utilitarian.
But that doesn't mean van der Rohe didn't have any eye for detail. The all-glass lobby was very deliberate, to tie in the granite tiles of the plaza to the granite walls in the lobby. Black i-beams that run up the side of the building, while looking very industrial, are completely ornamental.
Check this out: As a testament to van der Rohe's dedication to detail, stand in the plaza and face the building -- with your eye, follow any line between the granite tiles and you'll see they match up perfectly with the i-beams to create a continuous line from the ground all the way up the building.