Aon Center

Chicago, United States

Exterior only

Visible from the street; the inside is private.

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The Aon Center is a 1,136-foot supertall skyscraper dominating the Northeast corner of the Chicago Loop, designed by Edward Durell Stone in partnership with Perkins and Will and completed in 1973. Originally known as the Standard Oil Building, this 83-story modern structure briefly held the title of Chicago's tallest building before being surpassed by the Sears Tower. Now the fourth-tallest in Chicago, it houses the headquarters of Aon, Blue Cross Blue Shield Association, and Kraft Heinz, and is managed by JLL, which maintains its own headquarters within the building. The structure previously served as the world headquarters of Amoco until the company's merger with BP.