There are a few interesting modern buildings on the Northwestern University campus in Evanston, Illinois. Several were designed by Walter Netsch of Skidmore Owings and Merrill, noted for several of the firms other prominent buildings from the 1950s through the 1970s.
The Rebecca Crown Center was constructed in 1968 as administrative offices. Centered on a plaza above street level and accessible by staircases from different locations, its an interesting and slightly disorienting experience. The complex is dominated by a 100 foot tall Brutalist-style clock tower.
University Library, opened in 1970, is made up of three separate cores and is situated in such a way as to be seen from many different vantage points.
Most of the information for this post was culled from the excellent Northwestern architecture site here.