Designed by Louis Sullivan and his protégé Frank Lloyd Wright, this almost austere residence is one of the few extant buildings that displays the combined talents of these two architectural innovators. Historians still squabble about who contributed what here, but it's easy to imagine that the young go-getter had a hand in the cleanly rendered interior. Note how the geometric exterior looks unmistakably modern next to its fussy neighbors. Public tours of both the interior and exterior are available and last about one hour. The complimentary Wednesday tours are less comprehensive than the $10 ones on Saturday; reservations are a good idea for large groups.