The Chicago Architecture Foundation is a must see if you are an architecture fanatic or just love the Chicago skyline.
The CAF has a great shop inside the Historic Santa Fe Building in downtown Chicago. They sell informative books about architecture, fun Chicago souvenirs, kids toys and more.
Enter off of Michigan Avenue and after stopping at their great shop head back through a door into a grand atrium that houses a large scale model of Chicago. The model is up to the nearest detail and is checked every year to make sure it is up to date. The atrium also houses kids programs and many innovative exhibits about Chicago and its buildings.