Aon Center (Chicago)

For the skyscraper in Los Angeles, see Aon Center (Los Angeles).

Aon Center
The Aon Center, designed by Edward Durell Stone, in February 2005
General information
Status	Complete
Type	Office
Location	200 E. Randolph St. Chicago, Illinois 60601, United States
Coordinates
Construction started	1970
Opening	1973
Cost	$120,000,000 (USD)
Owner	Piedmont Office Realty Trust
Height
Architectural	346.3 m (1,136 ft)
Tip	362.5 m (1,189 ft)
Top floor	328 m (1,076 ft)
Technical details
Floor count	83 above ground 5 belowground
Floor area	3,600,000 sq ft (334,451 m2)
Lifts/elevators	50, made by Otis Elevator Company
Design and construction
Architect	Edward Durell Stone
Developer	Standard Oil of Indiana
Main contractor	Turner Construction
References

The Aon Center (200 East Randolph Street, formerly Amoco Building) is a modern supertall skyscraper in the Chicago Loop, Chicago, Illinois, United States, designed by architect firms Edward Durell Stone and The Perkins and Will partnership, and completed in 1974 as the Standard Oil Building. With 83 floors and a height of 1,136 feet (346 m), it is the third tallest building in Chicago, surpassed in height by the Willis Tower and the Trump International Hotel and Tower. The building is managed by Jones Lang LaSalle, which is also headquartered in the building. Aon Center formerly had the headquarters of Aon and Amoco; Aon's US operations are still headquartered here.

History

Alternate views

from southwest

from south

Construction

The Standard Oil Building was constructed as the new headquarters of the Standard Oil Company of Indiana, which had previously been housed at South Michigan Avenue and East 9th Street. When it was completed in 1974 it was the tallest building in Chicago and the fourth-tallest in the world, earning it the nickname "Big Stan". (A year later, the Sears Tower took the title as Chicago's and world's tallest.) The building employs a tubular steel-framed structural system with V-shaped perimeter columns to resist earthquakes, reduce sway, minimize column bending, and maximize column-free space. This construction method was also used for the former World Trade Center towers in New York City.

Refacing

When completed, it was the world's tallest marble-clad building, being sheathed entirely with 43,000 slabs of Italian Carrara marble. The marble used was thinner than previously attempted in cladding a building; this quickly proved to be a mistake. On December 25, 1973, during construction a 350-pound marble slab detached from the façade and penetrated the roof of the nearby Prudential Center. In 1985, inspection found numerous cracks and bowing in the marble cladding of the building. To alleviate the problem, stainless steel straps were added to hold the marble in place. Later, from 1990 to 1992, the entire building was refaced with Mount Airy white granite at an estimated cost of over $80 million. (Amoco was reluctant to divulge the actual amount, but it was well over half the original price of the building, without adjustment for inflation.) Two-thirds of the discarded marble was crushed and used as landscaping decoration at Amoco's refinery in Whiting, Indiana, one-sixth was donated to Governors State University, in University Park, Illinois, and one-sixth donated to Regalo, a division of Lashcon Inc. Under a grant from the Illinois Department of Rehabilitative Services, Regalo's 25 handicapped workers carved the discarded marble into a variety of specialty items such as corporate gifts and mementos including desk clocks and pen holders. The building's facade now somewhat resembles that of the former World Trade Center due to the upward flow of the columns.

Designation

The Standard Oil Building was renamed the Amoco Building when the company changed names in 1985. In 1998, Amoco sold the building to The Blackstone Group for an undisclosed amount, estimated to be between $430 and $440 million. It was renamed as the Aon Center on December 30, 1999, although the Aon Corporation would not become the building's primary tenant until September 2001. In May 2003, Wells Real Estate Investment Trust, Inc. acquired the building for between $465 and $475 million. (On August 10, 2007, Wells Real Estate Investment Trust, Inc. changed its name to Piedmont Office Realty Trust, Inc.)

Looking up the building from the ground.

Exterior lighting

In recent years, the top floors of the building have been lit at night with colors to reflect a particular season or holiday. Orange is used for Thanksgiving, green or red for Christmas, and pink during National Breast Cancer Awareness Month. The lighting commonly matches the nighttime lighting on the antenna of Willis Tower, the John Hancock Center and the upper floors of the Merchandise Mart.

Plaza

In the plaza, there is a sounding sculpture by Harry Bertoia.

See also

• Aon Center (Los Angeles)
• List of buildings
• List of skyscrapers
• List of tallest buildings and structures in the world
• List of tallest buildings in Chicago
• List of tallest buildings in the United States
• List of tallest freestanding structures in the world

External links

• Aon Center on CTBUH Skyscraper Center
• List of tenants at the Aon Center - Companies located at 200 East Randolph Street, Chicago IL

Preceded by John Hancock Center	Tallest building in Chicago 1972–1973 346 m	Succeeded by Willis Tower
	Tallest building in the United States outside of New York City 1972–1973 346 m