What with Louis Sullivan buildings burning one after another, it’s never seemed more important to become well versed in Chicago’s architectural history. The Chicago Loop Alliance, a group of schools and businesses whose mission is to promote the downtown area, offers three free “Loop the Loop” audio tours–of landmark buildings, public art, and theaters–that you can download to an MP3 player. You can walk around with them at your own pace or listen at home on a rainy day, following along on an interactive online map. The tours vary in the number of stops, but expect to spend about an hour on foot for each.