Second City skyline

Known as the Loop, Chicago's central business district along Lake Michigan is the largest in the United States outside New York City. With its neighbor districts, the Near North and Near South Sides, it boasts most of the skyline's impressive tally of 135 skyscrapers. Chicago's known as the Second City, but in 1885 became the first to build a skyscraper: the Home Insurance Building. The city's architectural fame apexed in 1973 when the Sears Tower topped out, beginning its nearly quarter-century reign as the world's tallest building. Now named the Willis Tower and still Chicago's high point, the 110-story glass giant looms out of frame off to our left.