The Chicago Building is a prime example of Chicago School architecture.
Beginning in the early 1880s, architectural pioneers of the Chicago School explored steel-frame construction and, in the 1890s, the use of large areas of plate glass. These were among the first modern skyscrapers. William LeBaron Jenney's Home Insurance Building was completed in 1885 and is considered to be the first to use steel in its structural frame instead of cast iron, but this building was still clad in heavy brick and stone. However, the Montauk Building, designed by John Wellborn Root Sr. and Daniel Burnham, was built in 1882–1883 using structural steel. Daniel Burnham and his partners, John Welborn Root and Charles Atwood, designed technically advanced steel frames with glass and terra cotta skins in the mid-1890s, in particular the Reliance Building; these were made possible by professional engineers, in particular E. C. Shankland, and modern contractors, in particular George A. Fuller.
Louis Sullivan was perhaps the city's most philosophical architect. Realizing that the skyscraper represented a new form of architecture, he discarded historical precedent and designed buildings that emphasized their vertical nature. This new form of architecture, by Jenney, Burnham, Sullivan, and others, became known as the "Commercial Style," but it was called the "Chicago School" by later historians.
In 1892, the Masonic Temple surpassed the New York World Building, breaking its two-year reign as the tallest skyscraper, only to be surpassed itself two years later by another New York building.