Sears Tower: 35th Anniversary Edition

“She towers so high,” were the memorable words sung by a chorus of electrical workers as the final white beam with over 12,000 signatures was lifted into the sky during the legendary topping out ceremony for Sears Tower on May 3, 1973 — exactly 35 years ago. The conditions were cold, but clear as thousands of eager visitors waited in anticipation while steelworkers more than 1,000 feet above the surrounding streets began bolting the beam into place.

Since that time, Sears Tower has become the destination for millions of world tourists and a daily center of work and commerce for thousands of Chicagoans. Sears Tower has also served as a frequent backdrop to numerous groundbreaking films from Ferris Bueller's Day Off (1986) to The Fugitive (1993), it has been scaled by such daring acrobats as Spider Dan (1981) and Alain "Spiderman" Robert (1998), it has been a highlight of media controversy in response to the CTBUH (1997), it has been a center of preparations for making Chicago HDTV capable (2000), it has been placed on the city's list of focal points for protecting against terrorism (2003), and most recently it has been cited as a prospective new headquarters for the U.S. Olympic Committee (2008).

Sears Tower truly is both a distinguished landmark and a principal engineering accomplishment of the modern age — and in following the human quest to reach ever higher, Sears Tower continues to astound and marvel its visitors to this day. Please join me in commemorating an exciting thirty-five years. Here's “Looking Up” to a prosperous future!

Randall E. Krause
May 3, 2008

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The Big Store seen from Lake Michigan (© Randall Krause)

Sears Tower stands tall, over 1,700 feet aloft, overlooking the west side of Chicago's downtown Loop. Clad in bronze-tinted glass and stainless aluminum, rising with determination yet elegance from the depths of its grand foundations to the tips of its massive spires, luring tourists in daze, housing a workforce of thousands, the Big Store represents an era in Chicago of optimism and opportunity that will not be forgotten.

Did You Know officially launched in 1998, just over ten years ago, making it the longest running enthusiast site for any skyscraper in the world.


Early Years

Modern versus classic in Chicago's Loop (© Randall Krause)

Originally designed in the late 60's by Bruce Graham of Skidmore, Owings, and Merrill for Chicago-based Sears, Roebuck and Co, Sears Tower was topped out in May of 1973 — just over 35 years ago.

During the skyscraper's initial construction, which began in August of 1970, two other prominent office tower projects vied for the "world's tallest" title: the Standard Oil of Indiana Building (now the Aon Center) located in downtown Chicago and the World Trade Center high-rise complex formerly located in Manhattan. Both were surpassed within their first year of completion by Sears Tower.

In 1984, SOM was commissioned to overhaul many of the tower's lower-levels, including the addition of a vaulted atrium alongside Wacker Drive. Following Sears' departure, the building underwent a comprehensive renovation by DeStefano + Assoc of all public and Skydeck lobbies and elevators. This also included the construction of two glass-and-steel canopies over the Franklin Street and Jackson Street entrances. By the fall of 1995, a seasonal rooftop illumination program was also initiated.

Sears Tower was the last supertall building constructed during the International architecture period, and SOM's interpretation of the style is remarkably bold and awe-inspiring.

The superstructure consists of nine interlocking tubes that terminate at different heights, creating the iconic stepped-back appearance of the tower. Each tube is a rigid steel frame that performs in tandem with its neighbor to efficiently counteract all lateral and gravity loads. (This is in contrast to the popular tube-in-tube system, in which a rigid network of floor diaphrams and closely-spaced exterior columns work in unison to resist lateral loads whereas a centralized core functions to carry vertical loads exclusively.)

This "bundled-tube" configuration was a revolutionary engineering concept at the time, pioneered by SOM's very own Fazlur R. Khan. It allowed for large open office spaces on the lower levels, where Sears, Roebuck and Company would reside, and smaller floor plates on the upper levels with unobstructed views of the cityscape. To aid in occupant comfort, belt trusses were rigged on the upper mechanical floors thereby further reducing shear forces (i.e. wind-induced sway).

Building automation was a primary design consideration as well. For fire, security, and HVAC monitoring and control, engineers opted for a Honeywell computer system, one of the largest such networks ever installed at the time. Another technological innovation was the robotic window washers that could be programmed to descend along tracks built into the curtain wall. Currently, they operate eight times per year.

Sears Tower also provides facilities for broadcasting to the Chicago metropolitan area. Twin 85-foot cylindrical supports, both 12-feet in diameter, project from inside the roof to provide a rigid steel base for 159-foot triangular communication towers each of which is encased in white fiberglass radome, extending the full building height. The 101st floor is leased to broadcasters for housing of transmitter equipment.

Vertical transporation was also crucial. Designers had to ensure efficient flow of pedestrian traffic throughout the building — which, on any given day, could number in the tens of thousands. Westinghouse Electric Corp. employed "skylobbies" for this purpose, a system which Otis Elevator Co. had originally implemented in Chicago's own John Hancock Center. Designated transfer-floors would be served by banks of double-deck express elevators. Separate banks of local-service elevators would carry passengers to their final destination.


Modern Day

Looking skywards on South Wacker Drive (© Randall Krause)

Sears eventually chose to move its headquarters to a more human-scale suburban setting in Hoffman Estates leaving the tower nearly half vacant. Management and leasing of the property was initially given to Chicago developer John Buck Co. — who established the iconic building as a destination for many new tenants over the course of almost five years.

The building was first acquired in 1989 by Boston's AEW Capital Management for the sum of $800 million. However, despite successfully bringing occupancy up by 40 percent during its term of ownership, AEW could not profit leasing space to its roster of tenants due to a continued downtown real estate depression and lower than average rental rates within the Tower.

In late 1997, the landmark tower was sold for $804 million to Toronto-based TrizecHahn, a REIT (real estate investment trust) firm. Downtown property markets subsequently began to show signs of recovery, and Sears Tower was again becoming one of Chicago's most prestigious high-rise properties. In fact, to honor Sears Tower's principal structural engineer, an adjacent street was, following a ceremony in the building, dedicated "Fazlur R. Khan Way" on July 7, 1998 by the City of Chicago.

Sears Tower, alongside John Hancock Center and Amoco Building, was the epitome of the Chicago skyscraper craze during the latter half of the 20th century — a time when the American economy was booming and tall buildings were a sign of commercial strength and success.

To meet the growing demands of the digital age, Sears Tower was upgraded March 8 of 2000 with four combination antennas, each 29.4-feet, 2890-lbs mounted on 80-foot towers at the four corners of the roof. An Erickson S-64F Aircrane was used to lift the load from the top of the parking garage skyward about one quarter mile. Four city blocks were closed off during the massive operation. However, the addition would ensure that the Chicago area was capable of receiving HDTV.

On June 4, 2000, the 220-foot western communications tower had to undergo modifications to increase the signal quality of Chicago's local NBC television station. This necessitated disassembling the existing framework via hellicopter and installing a new 75-foot, 19250-lb stack of self-supporting antenna pylons for WMAQ-29, WLS-52, and WPWR-52/22 on top of the existing support tower, thus raising the height of the building to 1729 feet.

Following the attacks of September 11, 2001, however, the status of Sears Tower as a viable investment opportunity proved questionable. Trizec Properties Inc. finally transfered ownership to its lender, MetLife Inc., in August of 2003 after facing the growing possibility of defaulting on its mortgage. Less than one year later, however, MetLife sold its stake in the building outright to a group of three investors (including two of Larry Silverstein's group). The building is now managed by real estate firm CB Richard Ellis Inc. (CBRE).

Engineers sought different ways of emphasizing the city of ‘broad shoulders’, and the desire for Chicagoans (including their businesses) to always be bigger, bolder, and better. Sears Tower is perfectly reminiscient of a thriving, innovative period in Chicago architectural history.

The entire building has also undergone significant security improvements since 2001. Johnson Controls' Hillside office was awarded the contract to install various barricades along all street-level entrances, X-ray metal detectors in the main concourse, and electronic turnstile portals around the elevator lobby. Additionally, visitors now wishing to do business in the tower must sign-in at a security checkpoint. Any unidentified person will be immediately escorted out of the building by armed security officers.



As of 2008, Sears Tower remains the tallest skyscraper in the western hemisphere and the largest commercial-use office building (in rentable square footage) in the United States. Annually 1.3 million people visit the observation deck alone, making the "Big Store" the 7th most popular tourist destination in Chicago (Source: Chicago Tribune, Sept 14, 2006). In addition, a recent public poll conducted by the American Institute of Architects, in commemoration of its 150th anniversary, ranked Sears Tower as America's third favourite Chicago architectural landmark.

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Building Technical Data

Street Address:

233 South Wacker Drive

Postal Code:


Time Zone:

U.S. Central Standard Time (-0600 UTC)
U.S. Central Daylight Time (-0500 UTC)

Global Coordinates:

-87°38'11" Longitude
41°52'43" Latitude

Street Boundaries:

Wacker Drive
Franklin Street
Jackson Boulevard
Adams Street
Quincy Street (removed)

Average Occupancy:

10,200 Persons Daily

Average On-Site Traffic:

25,000 Persons Per Day

Property Manager:

U.S. Equities Realty LLC

Property Owners:

Joseph Moinian (New York)
Joseph Chetrit (New York)
John Huston (Illinois)


August 1970


May 1973

Initial Opening

September 1973


Sears, Roebuck & Co.

Chief Architectural Designer

Bruce Graham, Partner (SOM Chicago)

Principal Structural Engineer

Fazlur R. Khan (SOM Chicago)

Wind Analysis

Weidlinger Associates

Mechanical Engineer

Jaros, Baum, & Bolles

General Contractor

Diesel Construction (aka Morse-Diesel Inc.)

Electrical Engineer

Jaros, Baum & Bolles, Assoc.


American Bridge Division of US Steel


American Bridge Division of US Steel

Rental Agent

Cushman & Wakefield Inc.

Security Integrator

Johnson Controls, Inc.

Gross Floor Area:

~4.56 Million Sq Ft

Rentable Floor Area:

~3.81 Million Sq Ft

Parking Facilities:

160-Car Underground Garage (Wacker Drive)
1,010-Car Standalone Garage (Adams Street)

Occupiable Floor Levels:


Height Above Grade:

1729-Ft (from Franklin Street entrance)

Primary Architectural Style:


Primary Structural System:

Bundled Tube

Construction Materials:

Prefabricated Steel "Christmas Tree" Frame
Concrete and Steel Composite Floor Deck
Steel Truss Floor Joists

Cladding Material:

Bronze-Tinted Vision Glass
Black Anodized Aluminum Spandrel Panels
Black Anodized Aluminum Framing

Foundation Type:

Bell Reinforced-Concrete Caissons

AM/FM Radio Transmitters:


NOAA Wx Radio Transmitter:


Analog Television Transmitters:


Digital Television Transmitters:

WGN-DT-19 (WB)

Graphical comparison of Sears Tower to similar skyscrapers.

Recent news headlines about Sears Tower.

Historic news headlines about Sears Tower.

Awards and Acknowledgments:

  • "Distinguished Building Award", AIA, Chicago Chapter (1976)
  • "Award of Excellence", American Institute of Steel Construction (1975)
  • "Best Engineering, High Rise Construction Award", American Iron & Steel Institute (1975)

Visit the official homepage of

Twin Towers Alliance

Watch ABC7 Chicago's realtime Sears Tower skycams.

For those wondering about the title of the site, it is a play on 1001 Arabian Nights. And yes, storeys is an actual English word I chose for its spelling.

Copyright © 1998-2009, Randall E. Krause. Unauthorized reproduction prohibited.
This site is not affiliated with Sears, Roebuck and Co. nor Sears Tower.
The names "Sears" and "Sears Tower" may be protected by U.S. trademark.