A great off-the-wall tour to discover a part of Chicago that even many long time residents aren't familiar with. It's indoors, so it can be taken any time of the year comfortably. The tour guide, Margaret, is both funny and knowledgeable about the subterranean hallways below the city streets. Don't let the description scare you...you'll feel like you're walking through a mall. Lots of walking and some stairs, so bring comfortable shoes. We attended a free tour in January, but I feel it's well worth the normal cost. Our tour lasted just under an hour. Would definitely recommend this tour to friends.