From the outside, this gloomy building gives no hint of the beauty within. Designed by master architect Daniel Burnham in the 1880s, it was one of Chicago’s largest and most expensive office buildings when it was completed. (The name was a carryover from the old City Hall that previously occupied the site, a favorite of roosting birds.) In 1898, a young architect starting up an independent practice, Frank Lloyd Wright, rented an office here; a few years later, he was commissioned to update the building’s interior. The resulting work is one of the loveliest commercial interiors in the city, including a two-story glass pavilion filled with natural light and gleaming white marble. Tours are offered by the Frank Lloyd Wright Preservation Trust on Tuesdays, Thursdays, and Fridays; longer tours include the on-site library. The ShopWright store stocks a well-edited collection of books and decorative accessories. Allow 5 minutes for a quick look, up to 45 minutes if you stay for a tour.