Chicago is the largest city in both the state of Illinois and the Midwest, and the most populous city in the United States of America, with over 2.8 million residents. Chicago was founded in 1833, near a portage between the Great Lakes and the Mississippi River watershed. Globally recognised, Chicago has various nicknames, which reflect the impressions and opinions about historical and contemporary Chicago. The best known include: "Chi-town," "Windy City," "Second City," and the, "City of Big Shoulders."

Chicago gave its name to the Chicago School and was the home of the Prarie School movements in architecture and in 1885, the first steel-framed high rise building, the Home Insurance Building, rose ushering in the skyscraper era.