Chicago a city in the U.S. state of Illinois, is the third most populous city in the United States and the most populous city in the American Midwest, with approximately 2.7 million residents. Its metropolitan area (also called "Chicagoland"), which extends into Indiana and Wisconsin, is the third-largest in the United States, after those of New York City and Los Angeles, with an estimated 9.5 million people. Chicago is the county seat of Cook County, though a small portion of the city limits also extends into DuPage County.
Chicago was incorporated as a city in 1837, near a portage between the Great Lakes and the Mississippi River watershed. Today, Chicago is listed as an alpha+ global city by the Globalization and World Cities Research Network, and ranks seventh in the world in the 2012 Global Cities Index. The city is an international hub for finance, commerce, industry, telecommunications, and transportation, with O'Hare International Airport being the second-busiest airport in the world in terms of traffic movements.
In 2012, Chicago hosted 46.2 million international and domestic visitors. Among metropolitan areas, Chicago has the fourth-largest gross domestic product (GDP) in the world, just behind Tokyo, New York City, and Los Angeles, and ranking ahead of London and Paris. Chicago is one of the most important Worldwide Centers of Commerce and trade. Chicago's notability has found expression in numerous forms of popular culture, including novels, plays, films, and songs. The city has many nicknames, which reflect the impressions and opinions about historical and contemporary Chicago. The best-known include "Windy City" and "Second City."
In 2008, Chicago attracted 32.4 million domestic leisure travelers, 11.7 million domestic business travelers and 1.3 million overseas visitors. These visitors contributed more than US$11.8 billion to Chicago's economy. Upscale shopping along the Magnificent Mile and State Street, thousands of restaurants, as well as Chicago's eminent architecture, continue to draw tourists. The city is the United States' third-largest convention destination. A 2011 study by Walk Score ranked Chicago the fourth most walkable of fifty largest cities in the United States. Most conventions are held at McCormick Place, just south of Soldier Field. The historic Chicago Cultural Center (1897), originally serving as the Chicago Public Library, now houses the city's Visitor Information Center, galleries and exhibit halls.
The ceiling of its Preston Bradley Hall includes a 38 ft (12 m) Tiffany glass dome. Grant Park holds Millennium Park, Buckingham Fountain (1927), and the Art Institute of Chicago. The park also hosts the annual Taste of Chicago festival. In Millennium Park, there is the reflective Cloud Gate sculpture. Cloud Gate, a public sculpture by Indian-born British artist Anish Kapoor, is the centerpiece of the AT&T Plaza in Millennium Park. Also, an outdoor restaurant transforms into an ice rink in the winter season. Two tall glass sculptures make up the Crown Fountain.
The fountain's two towers display visual effects from LED images of Chicagoans' faces, along with water spouting from their lips. Frank Gehry's detailed, stainless steel band shell, the Jay Pritzker Pavilion, hosts the classical Grant Park Music Festival concert series. Behind the pavilion's stage is the Harris Theater for Music and Dance, an indoor venue for mid-sized performing arts companies, including the Chicago Opera Theater and Music of the Baroque.