This project of the well-known architecture firm of Burnham and Root is named for a temporary City Hall and water tank that stood on the site following the Fire of 1871, but we prefer to think it's dubbed for the pigeons that roost there. In further famed-facts, Frank Lloyd Wright remodeled the Rookery's large skylit lobby in 1905, introducing elements characteristic of his Prairie School designs. But inside and out, it's a fantasy of red stone, marble, gold leaf, bronze and a sun roof. And it's free.