During the 1880's and '90s, Chicago architects designed buildings with exteriors clearly expressing their innovative steel-frame construction. These "Chicago School" buildings have been praised as important precursors to 20th-century steel-and-glass skyscrapers. In Chicago, most examples of the style are office buildings in the Loop.

Common characteristics are:

• steel-frame construction
• masonry cladding, usually terra cotta, clearly emphasizing the steel framing
• distinctive three-part windows, with large central fixed panes flanked by smaller double-hung sash windows
• minimal use of ornament

1.	Carson Pirie Scott Windows, photo by Richard Nickel