When I was in Chicago for Quilt Festival I was able to take a day and go into the city. My daughter and I took a two hour tour entitled "Architecture and Commerce" that was fascinating! Our guide took us through stores, hotels and into what was once the City Library to see interesting details in structures and facaeds. I'd highly recommend a guided tour to see spots that we wouldn't normally find on our own.
Here's some pictures of the ceiling of Macy's Department store, a fence around a city garden (perfect for my Stained Glass designs) and an arch in the Chicago Cultural Centre. I was so excited by seeing all these wonderful design concepts! I'll be busy for ages!