The Aon Center, originally called the Standard Oil building, is one of the tallest skyscrapers in Chicago.

Chicago  Mayor Richard J. Daley inspects the plans

Mayor Richard J. Daley and John Swearingen, President of Standard Oil, view an architectural model of the Standard Oil Building (now Aon Center), circa 1967

Mayor Richard J. Daley and John Swearingen, President of Standard Oil, view an architectural model of the Standard Oil Building (now Aon Center), circa 1967. RJD_04_01_0026_0020_001

Groundbreaking!

Mayor Richard J. Daley and John Swearingen, President of Standard Oil, stand next to an architectural model of the Standard Oil Building (now Aon Center) at the groundbreaking ceremony for that building. Two unidentified men are behind them at the right, 1967

Mayor Richard J. Daley and John Swearingen, President of Standard Oil, stand next to an architectural model of the Standard Oil Building (now Aon Center) at the groundbreaking ceremony for that building. Two unidentified men are behind them at the right, 1967. RJD_04_01_0026_0020_002

Architectural drawings

Architectural rendering of the Aon Center Plaza showing a square pool with fountains and flags of the fifty states, circa 1970s

Architectural rendering of the Aon Center Plaza showing a square pool with fountains and flags of the fifty states, circa 1970s. RJD_04_01_0038_0013_002

Architectural rendering of the Aon Center Plaza on Randolph Street, showing the work "Sounding Sculpture" by Harry Bertoia with cascades of water around the ventilating elements, circa 1970s

Architectural rendering of the Aon Center Plaza on Randolph Street, showing the work “Sounding Sculpture” by Harry Bertoia with cascades of water around the ventilating elements, circa 1970s. RJD_04_01_0038_0013_001