The third largest city in the U.S. behind Los Angeles and New York, Chicago has a population of around 2.9 million with 9.3 million residing in the Chicago metro area. The "Windy City" is headquarters to many Fortune 500 companies and is the economic and cultural center of the Midwest. It is also home to world-famous attractions like the Sears Tower, Navy Pier, Michigan Avenue and Millennium Park. Chicago's O'Hare airport is a major airline hub.