The Chicago River tour is like visiting the world's museum of skyscraper architcutre and is especially nice at sunset. Easily one of the coolest things we did when we visited last year!
The prominent green glass building following the curve of the river is 333 Wacker Drive. This is one of the most famous all-glass skyscrapers in the world and the design made architects Kohn Pedersen Fox famous. You might remember this skyscraper from Ferris Bueller's Day Off with Ferris Bueller's father's offices inside and it was also apparently voted "Favorite Building" by the readers of The Chicago Tribune in 1995.