Daley Center (1965): In my opinion, the epitome of high modern for the latter half of the 20th century, this building expresses itself like few others. The Cor-ten Steel has developed a rich brown patina over the decades. One funny thing, I never noticed that the columns grow narrower as the ascend to the top of the building.
This support column at Contemporaine (2003) helps make for an impressive, yet subdued entrance for the residents.
200 South Wacker Drive (1981) thrusts it corner out over the sidewalk, giving a view towards the top not often available on other high-rises.
Wrigley Building (1923-23): I would imagine this 14th floor skybridge was quite unique in 1925 when it was constructed between the two towers commonly thought of as one.