Chicago got a jump on skyscraper design after a fire devastated much of the city in 1871. The stone-and-steel towers, which were more fireproof than earlier wooden structures, provided an efficient way to rebuild the city. These pioneering structures housed a greater number of offices and apartments than the smaller structures that had burned down, but they took up the same amount of available land. Over the next few decades, skyscrapers transformed the Windy City into a modern metropolis at the forefront of American architecture.

The architects of these new buildings were referred to as the Chicago School -- even though all of them came from somewhere else. One of their favorite elements was a type of large horizontal window that came to be known as the Chicago window. It had a fixed pane in the center and narrower, movable sash windows on the sides. The following are some of the most significant buildings created by the Chicago School.

The Rookery stands at the corner of La Salle and Adams streets. It was nicknamed "the Rookery" after the pigeons and the politicians who roosted in the building. From the outside, the Rookery looks fairly conventional: built of granite and brick that's shaped into turrets and other historical details. But it takes advantage of such innovations as fireproof clay tile, plate glass, and the hydraulic passenger elevator. At the building's center, a courtyard lobby with a huge skylight is surrounded by surfaces of light-reflective glazed brick and terra cotta. Contemporary writers praised the Rookery as "the most modern of office buildings" and "a thing of light." In 1905, Frank Lloyd Wright renovated the ground-floor lobby in the courtyard with geometric ornaments and light fixtures. Many of these features, along with the original facades, were restored in 1992.

The 16-story Monadnock Building (Jackson Blvd. and Dearborn) was the last skyscraper in Chicago to be constructed with load-bearing walls of brick. To carry the upper floors, the walls at ground level were built six feet thick. Although the building is old-fashioned in its construction, the tapering tower is modern in its lack of exterior ornamentation. Rising inward and upward to an outwardly flaring cornice, it was once compared to an Egyptian column. In 1893, the building was expanded with a steel-framed addition.

The 14-story Reliance Building (North State St. and Calhoun) marked a new breakthrough in skyscraper design. Its exterior walls are almost entirely composed of large Chicago windows. Between the windows, narrow bands of cream-colored terra cotta clearly correspond to the grid of the steel skeleton frame underneath. This light and airy architecture, which paved the way for today's glass-and-steel skyscrapers, was a radical departure from the heavier masonry buildings of the time. After decades of neglect, the Reliance Building was restored in 1999 and turned into a 122-room hotel.