A skeletal, rectangular style of the first five-to fifteen-story skyscrapers brought to full form in Chicago, New York, and Philadelphia. It was characterized by flat roofs, and minimal ornament, except for slight variations in the spacing of windows. Extensive use of glass was made possible by its steel-frame construction, which could bear the structural loads that masonry could not.
A style of commercial architecture developed by the Chicago School, applied primarily to multistory office buildings and mercantile buildings constructed from about 1875 to 1930. Usually characterized by a tripartite scheme consisting of a base that is one to three stories high, a shaft many stories high; and a cap, usually one to three stories high that tops the structure; a flat roof; an overhanging cornice; unadorned fenestration, most often with large rectangular windows (for example, see Chicago window); bay windows with decorative spandrels, 1. Sometimes called Chicago Commercial style.