In Chicago, one of the best things is the architecture of the buildings. I recommend walking along Wacker Dr. and staring around. The Millenium Park (at the end of Wacker) looks surreal. Then you probably want to go up into Sears tower, and shop along the Magnificent Mile. And there are several huge statues made by Picasso and Miro, that are placed outside in public places. But I strongly recommend buying a guide book, as there are too many interesting things that you don't want to miss. At least, not if you like modern design. Chicago also has gorgeous art galleries, and one of the largest museums of art. Again, the emphasis is on modern/contemporary art - so if that's your thing, this is THE city to visit. And even if it's not your thing, there are still plenty of sights that steal your breath away. Enjoy your vacation!