Architecture of Chicago in the context of Polish Cathedral Style

Chicago is the most populous city in the U.S. state of Illinois and in the Midwestern United States. Located on the western shore of Lake Michigan, it is the third-most populous city in the United States, with a population of 2.74 million at the 2020 census. The Chicago metropolitan area has 9.41 million residents and is the third-largest metropolitan area in the country. Chicago is the seat of Cook County, the second-most populous county in the U.S.

Chicago was incorporated as a city in 1837 near a portage between the Great Lakes and the Mississippi River watershed. It grew rapidly in the mid-19th century. In 1871, the Great Chicago Fire destroyed several square miles and left more than 100,000 homeless, but Chicago's population continued to grow. Chicago made noted contributions to urban planning and architecture, such as the Chicago School, the development of the City Beautiful movement, and the steel-framed skyscraper.

The Chicago School refers to two architectural styles derived from the architecture of Chicago. In the history of architecture, the first Chicago School was a school of architects active in Chicago in the late 19th, and at the turn of the 20th century. They were among the first to promote the new technologies of steel-frame construction in commercial buildings, and developed a spatial esthetic which co-evolved with, and then came to influence, parallel developments in European Modernism. Much of its early work is also known as Commercial Style.

A "Second Chicago School" with a modernist esthetic emerged in the 1940s through 1970s, which pioneered new building technologies and structural systems, such as the tube-frame structure.