23
Global
Height rank

Willis Tower

Chicago
Height
1
To Tip:

Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the highest point of the building, irrespective of material or function of the highest element (i.e., including antennae, flagpoles, signage and other functional-technical equipment).

527 m / 1,729 ft
2
Architectural:

Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the architectural top of the building, including spires, but not including antennae, signage, flag poles or other functional-technical equipment. This measurement is the most widely utilized and is employed to define the Council on Tall Buildings and Urban Habitat (CTBUH) rankings of the "World's Tallest Buildings."

442.1 m / 1,451 ft
3
Occupied:

Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the highest occupied floor within the building.

412.7 m / 1,354 ft
1 2 3 Willis Tower Outline
Floors
Above Ground

The number of floors above ground should include the ground floor level and be the number of main floors above ground, including any significant mezzanine floors and major mechanical plant floors. Mechanical mezzanines should not be included if they have a significantly smaller floor area than the major floors below. Similarly, mechanical penthouses or plant rooms protruding above the general roof area should not be counted. Note: CTBUH floor counts may differ from published accounts, as it is common in some regions of the world for certain floor levels not to be included (e.g., the level 4, 14, 24, etc. in Hong Kong).

108
Below Ground

The number of floors below ground should include all major floors located below the ground floor level.

3
Height 442.1 m / 1,451 ft
Floors 108
Official Name
The current legal building name.

Willis Tower

Other Names
Other names the building has commonly been known as, including former names, common informal names, local names, etc.

Sears Tower

Type
CTBUH collects data on two major types of tall structures: 'Buildings' and 'Telecommunications / Observation Towers.' A 'Building' is a structure where at least 50% of the height is occupied by usable floor area. A 'Telecommunications / Observation Tower' is a structure where less than 50% of the structure's height is occupied by usable floor area. Only 'Buildings' are eligible for the CTBUH 'Tallest Buildings' lists.

Building

Status
Completed
Architecturally Topped Out
Structurally Topped Out
Under Construction
Proposed
On Hold
Never Completed
Vision
Competition Entry
Canceled
Proposed Renovation
Under Renovation
Renovated
Under Demolition
Demolished

Completed, 1974

Country
The CTBUH follows the United Nations's definition of Country, and thus uses the lists and codes established by that organization.

United States

City
The CTBUH follows the United Nations's definition of City, and thus uses the lists and codes established by that organization.

Chicago

Postal Code

60606

Function
A single-function tall building is defined as one where 85% or more of its usable floor area is dedicated to a single usage. Thus a building with 90% office floor area would be said to be an "office" building, irrespective of other minor functions it may also contain.

A mixed-use tall building contains two or more functions (or uses), where each of the functions occupy a significant proportion of the tower's total space. Support areas such as car parks and mechanical plant space do not constitute mixed-use functions. Functions are denoted on CTBUH "Tallest Building" lists in descending order, e.g., "hotel/office" indicates hotel function above office function.

office

Structural Material
Steel
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from steel. Note that a building of steel construction with a floor system of concrete planks or concrete slab on top of steel beams is still considered a “steel” structure as the concrete elements are not acting as the primary structure.

Reinforced Concrete
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from concrete which has been cast in place and utilizes steel reinforcement bars.

Precast Concrete
Both the main vertical/lateral structural elements and the floor spanning system are constructed from steel reinforced concrete which has been precast as individual components and assembled together on-site.

Mixed-Structure
Utilizes distinct systems (e.g. steel, concrete, timber), one on top of the other. For example, a steel/concrete indicates a steel structural system located on top of a concrete structural system, with the opposite true of concrete/steel.

Composite
A combination of materials (e.g. steel, concrete, timber) are used together in the main structural elements. Examples include buildings which utilize: steel columns with a floor system of reinforced concrete beams; a steel frame system with a concrete core; concrete-encased steel columns; concrete-filled steel tubes; etc. Where known, the CTBUH database breaks out the materials used in a composite building’s core, columns, and floor spanning separately.

steel

Energy Label

LEED Recertification Platinum (2019), LEED Gold O+M: Existing Buildings (2016)

Official Website

Willis Tower

Height
Architectural
Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the architectural top of the building, including spires, but not including antennae, signage, flag poles or other functional-technical equipment. This measurement is the most widely utilized and is employed to define the Council on Tall Buildings and Urban Habitat (CTBUH) rankings of the "World's Tallest Buildings."

442.1 m / 1,451 ft

To Tip
Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the highest point of the building, irrespective of material or function of the highest element (i.e., including antennae, flagpoles, signage and other functional-technical equipment).
527.0 m / 1,729 ft
Occupied
Height is measured from the level of the lowest, significant, open-air, pedestrian entrance to the highest occupied floor within the building.
412.7 m / 1,354 ft
Observatory
412.7 m / 1,354 ft
Floors Above Ground
The number of floors above ground should include the ground floor level and be the number of main floors above ground, including any significant mezzanine floors and major mechanical plant floors. Mechanical mezzanines should not be included if they have a significantly smaller floor area than the major floors below. Similarly, mechanical penthouses or plant rooms protruding above the general roof area should not be counted. Note: CTBUH floor counts may differ from published accounts, as it is common in some regions of the world for certain floor levels not to be included (e.g., the level 4, 14, 24, etc. in Hong Kong).

108

Floors Below Ground
The number of floors below ground should include all major floors located below the ground floor level.

3

# of Elevators
Number of Elevators refers to the total number of elevator cars (not shafts) contained within a particular building (including public, private and freight elevators).

104

Top Elevator Speed
Top Elevator Speed refers to the top speed capable of being achieved by an elevator within a particular building, measured in meters per second.

8.1 m/s

Tower GFA
Tower GFA refers to the total gross floor area within the tower footprint, not including adjoining podiums, connected buildings or other towers within the development.

423,638 m² / 4,560,001 ft²

Rankings
#
23
Tallest in the World
#
3
Tallest in North America
#
3
Tallest in United States
#
1
Tallest in Chicago
#
9
Tallest Office Building in the World
#
2
Tallest Office Building in North America
#
2
Tallest Office Building in United States
#
1
Tallest Office Building in Chicago
#
1
Tallest Steel Building in the World
#
1
Tallest Steel Building in North America
#
1
Tallest Steel Building in United States
#
1
Tallest Steel Building in Chicago
Construction Schedule
1970

Construction Start

1974

Completed

2016

Retrofit Start

2021

Retrofit End

Architect
Design

Usually involved in the front end design, with a "typical" condition being that of a leadership role through either Schematic Design or Design Development, and then a monitoring role through the CD and CA phases.

Structural Engineer
Design

The Design Engineer is usually involved in the front end design, typically taking the leadership role in the Schematic Design and Design Development, and then a monitoring role through the CD and CA phases.

MEP Engineer
Design

The Design Engineer is usually involved in the front end design, typically taking the leadership role in the Schematic Design and Design Development, and then a monitoring role through the CD and CA phases.

Other Consultant

Other Consultant refers to other organizations which provided significant consultation services for a building project (e.g. wind consultants, environmental consultants, fire and life safety consultants, etc).

Façade

These are firms that consult on the design of a building's façade. May often be referred to as "Cladding," "Envelope," "Exterior Wall," or "Curtain Wall" Consultant, however, for consistency CTBUH uses the term "Façade Consultant" exclusively.

Property Management
Material Supplier

Material Supplier refers to organizations which supplied significant systems/materials for a building project (e.g. elevator suppliers, facade suppliers, etc).

Cladding
Elevator

Retrofit Companies Involved

Architect
Design

Usually involved in the front end design, with a "typical" condition being that of a leadership role through either Schematic Design or Design Development, and then a monitoring role through the CD and CA phases.

Structural Engineer
Design

The Design Engineer is usually involved in the front end design, typically taking the leadership role in the Schematic Design and Design Development, and then a monitoring role through the CD and CA phases.

MEP Engineer
Engineer of Record

The Engineer of Record takes the balance of the engineering effort not executed by the “Design Engineer,” typically responsible for construction documents, conforming to local codes, etc.

Contractor
Main Contractor

The main contractor is the supervisory contractor of all construction work on a project, management of sub-contractors and vendors, etc. May be referred to as "Construction Manager," however, for consistency CTBUH uses the term "Main Contractor" exclusively.

Other Consultant

Other Consultant refers to other organizations which provided significant consultation services for a building project (e.g. wind consultants, environmental consultants, fire and life safety consultants, etc).

Material Supplier

Material Supplier refers to organizations which supplied significant systems/materials for a building project (e.g. elevator suppliers, facade suppliers, etc).

Owner
Current
The Blackstone Group L.P.
Past
The Moinian Group
Developer
Sears Roebuck and Company
Architect
Design

Usually involved in the front end design, with a "typical" condition being that of a leadership role through either Schematic Design or Design Development, and then a monitoring role through the CD and CA phases.

Structural Engineer
Design

The Design Engineer is usually involved in the front end design, typically taking the leadership role in the Schematic Design and Design Development, and then a monitoring role through the CD and CA phases.

MEP Engineer
Design

The Design Engineer is usually involved in the front end design, typically taking the leadership role in the Schematic Design and Design Development, and then a monitoring role through the CD and CA phases.

Contractor
Main Contractor

The main contractor is the supervisory contractor of all construction work on a project, management of sub-contractors and vendors, etc. May be referred to as "Construction Manager," however, for consistency CTBUH uses the term "Main Contractor" exclusively.

Morse Diesel International
Other Consultant

Other Consultant refers to other organizations which provided significant consultation services for a building project (e.g. wind consultants, environmental consultants, fire and life safety consultants, etc).

Façade

These are firms that consult on the design of a building's façade. May often be referred to as "Cladding," "Envelope," "Exterior Wall," or "Curtain Wall" Consultant, however, for consistency CTBUH uses the term "Façade Consultant" exclusively.

Property Management
CBRE; EQ Office
Material Supplier

Material Supplier refers to organizations which supplied significant systems/materials for a building project (e.g. elevator suppliers, facade suppliers, etc).

Cladding
Elevator
Steel
American Bridge Company

Retrofit Companies Involved

Owner/Developer
The Blackstone Group L.P.
Architect
Design

Usually involved in the front end design, with a "typical" condition being that of a leadership role through either Schematic Design or Design Development, and then a monitoring role through the CD and CA phases.

Structural Engineer
Design

The Design Engineer is usually involved in the front end design, typically taking the leadership role in the Schematic Design and Design Development, and then a monitoring role through the CD and CA phases.

MEP Engineer
Engineer of Record

The Engineer of Record takes the balance of the engineering effort not executed by the “Design Engineer,” typically responsible for construction documents, conforming to local codes, etc.

Project Manager

The CTBUH lists a project manager when a specific firm has been commissioned to oversee this aspect of a tall building’s design/construction. When the project management efforts are handled by the developer, main contract, or architect, this field will be omitted.

EQ Office
Contractor
Main Contractor

The main contractor is the supervisory contractor of all construction work on a project, management of sub-contractors and vendors, etc. May be referred to as "Construction Manager," however, for consistency CTBUH uses the term "Main Contractor" exclusively.

Special Elements
Clark Construction Group
Other Consultant

Other Consultant refers to other organizations which provided significant consultation services for a building project (e.g. wind consultants, environmental consultants, fire and life safety consultants, etc).

Artist
Studio Olafur Eliasson
Energy Concept
Rivion
Observatory
Chicago Scenic Studios, Inc.; Skidmore, Owings & Merrill LLP; Thinc Design
Material Supplier

Material Supplier refers to organizations which supplied significant systems/materials for a building project (e.g. elevator suppliers, facade suppliers, etc).

CTBUH Initiatives

Videos

30 October 2017 | Chicago

Rethinking CTBUH's Height Criteria in the Context of Tall Timber

Recent developments in the design and construction of progressively taller buildings using engineered timber as a structural material raise important questions about the language that...

Research

25 June 2020

Curtain Wall Façades on the New Generation of Supertall Buildings Present and Future Directions

Sae Hwang Oh, Adrian Smith + Gordon Gill Architecture

Beginning in the late 19th century, construction of skyscrapers spread throughout Chicago, New York City, and then the world as demand of space in buildings...

Global News

23 April 2021

Skydeck at Chicago's Tallest Building Reopens Featuring a New Interactive Museum

EQ Office announced the exciting reopening of Skydeck Chicago at Willis Tower to the public on 23 April, 2021 after completing an extensive redevelopment. The...

About Willis Tower

The Willis Tower (formerly Sears Tower) in Chicago, with its signature black aluminum and bronze-tinted glare-reducing glass, was the tallest building in the world for nearly 25 years. Completed in 1974, Willis Tower set the standard for supertall skyscrapers around the globe, both in its innovative design and graceful styling. With approximately 424,000 square meters of gross floor area, the building is comparatively large for its height, with its foundation and the first 50 floors taking up an entire city block before the building begins to narrow.

The step-back design of the structure was designed by the architects as a direct result of Sears’ space requirements. The designers were required to develop a building that incorporated not only very large office floors, which were necessary to Sears’ operation, but also a variety of smaller floors which would be more suitable for tenants requiring less floor area. These requirements resulted in a bundled tube structure, the first of its kind. This innovative design was not only structurally efficient, but it also managed to be economical as well. It has proven to be a remarkably influential design typology, and has been used in most supertall buildings built since the Willis Tower, including the Burj Khalifa.

An assortment of features has kept the tower active, inviting, and efficient over its operational life. An undulating Alexander Calder sculpture greets office workers in the west lobby. Meanwhile, a 2009 addition to the observation deck affords visitors with vertigo-inducing views of Chicago via “The Ledge,” a series of boxes with transparent floors that extrude from the top of the building. Although the Willis Tower was built in an age before sustainable design matured, the building’s owners have recently implemented several sustainable elements, including low-flow fixtures that conserve more than 38 million liters of water annually, and high-efficiency lighting systems that help curb electrical loads.

Quick Facts

30 October 2017 | Chicago

Rethinking CTBUH's Height Criteria in the Context of Tall Timber

Recent developments in the design and construction of progressively taller buildings using engineered timber as a structural material raise important questions about the language that...

16 March 2017 | Chicago

Building Tall Skyscraper Lecture Series: How High Can We Go?

Thursday, March 16, 2017. Chicago, United States of America. Hosted in collaboration with the Chicago Architecture Foundation, the first lecture of the series Building Tall...

26 October 2015 | Chicago

Developing Tall in the New York Context

Gary Barnett, Extell Development Corporation; Ric Clark, Brookfield Properties; Joseph Moinian, Moinian Group; and Larry Silverstein, Silverstein Properties, discuss development in New York City and...

11 June 2013 | Chicago

From London to Chicago: The Willis Group and Tall Buildings

From the 1970’s seminal Willis Faber Dumas Ipswich building, through 51 Lime Street London (winner of the CTBUH 2008 Best Tall Building Europe award), to...

11 June 2013 | Chicago

Interview: Emerging Corporate Mobility

Carmine Bilardello of Willis Group is interviewed by Jeff Herzer during the 2013 CTBUH London Conference at The Brewery, London. Carmine talks about emerging corporate...

20 September 2012 | Chicago

Interview: Management of Tall Buildings

Tony Long of CBRE is interviewed by Jeff Herzer during the 2012 CTBUH Shanghai Congress at the Jin Mao, Shanghai. Tony talks about the management...

03 November 2011 | Chicago

Lynn S. Beedle Lifetime Achievement Award: 40 Years of Designing the Supertall

As one of the world’s foremost experts on supertall buildings, Adrian has contributed greatly to the development of this highly specialized building type. Adrian will...

10 October 2011 | Chicago

Tall Tales: Interrogating the typology of the Tall Building

The ongoing and ubiquitous project of modernism has acclimated humanity to the universality of the tall building as a type. Transformations and mutations of the...

23 October 2009 | Chicago

Chicago: 125 Years of Tall – Reflections

In the city where tall buildings began, this presentation highlights the historical trends, drivers and challenges behind tall buildings and sustainable urban development; what city...

23 October 2009 | Chicago

Interview: Retrofit of the Willis Tower

Adrian Smith & Gordon Gill of AS + GG Architecture are interviewed by Jeff Herzer during the 2009 CTBUH Chicago Conference at Illinois Institute of...

25 June 2020

Curtain Wall Façades on the New Generation of Supertall Buildings Present and Future Directions

Sae Hwang Oh, Adrian Smith + Gordon Gill Architecture

Beginning in the late 19th century, construction of skyscrapers spread throughout Chicago, New York City, and then the world as demand of space in buildings...

28 October 2019

Bringing an Icon into the Future: Willis Tower

Stephen Katz, Gensler

Few buildings are as iconic as Willis Tower. Generations of Chicagoans have a collective memory of this building playing a role in their entire lives....

28 October 2019

World’s Biggest (Tall) Buildings

Carol Willis, The Skyscraper Museum

In both professional circles and in the public eye, the subject of the World’s Tallest Building (WTB) has held the spotlight for more than a...

01 September 2018

Developments of Structural Systems Toward Mile-High Towers

Kyoung Sun Moon, Yale University School of Architecture

Tall buildings which began from about 40 m tall office towers in the late 19th century have evolved into mixed-use megatall towers over 800 m....

19 January 2016

Year in Review: Tall Trends of 2015

Jason Gabel, Marty Carver & Marshall Gerometta, CTBUH

CTBUH has determined that 106 buildings of 200 meters’ height or greater were completed around the world in 2015 – setting a new record for...

24 August 2015

World’s Highest Observation Decks

CTBUH Research

Perhaps no element of a tall building is more closely related to the pure pleasure of standing high in the sky and taking in the...

28 January 2014

Debating Tall: Antennas vs. Spires

Larry Silverstein, Siliverstein Properties Inc.; Dario Trabucco, IUAV University of Venice

The CTBUH’s Height Committee ratified the architectural height of One World Trade Center last November, touching off massive media coverage and opening up complicated mixed...

01 August 2013

Imagining the Tall Building of the Future

Josef Hargrave & Ralph Wilson, Arup

Predicting the future is an impossible task. One will never get it absolutely right. However, that does not make it a pointless exercise. Instead, such...

27 January 2012

Debating Tall: A Supertall Future in the US?

Adrian Smith, Adrian Smith + Gordon Gill Architecture; Paul Beitler, Beitler Real Estate Services LLC

In 1990, only 11 buildings in the world could be counted as a “supertall” (defined as a building over 300 meters tall), and all but...

13 April 2011

Tall and Urban: An Analysis of Global Population and Tall Buildings

CTBUH Research

Tall buildings are spreading across the globe at an ever-increasing rate. This study demonstrates the relationship between population and tall buildings across those countries and...

23 April 2021

Skydeck at Chicago's Tallest Building Reopens Featuring a New Interactive Museum

EQ Office announced the exciting reopening of Skydeck Chicago at Willis Tower to the public on 23 April, 2021 after completing an extensive redevelopment. The...

03 February 2021

Airline Reduces Chicago Tower Footprint After Sweeping COVID-19-Related Cuts

United Airlines is shrinking its Willis Tower headquarters, where it has about 30 percent fewer workers than before the COVID-19 pandemic. The airline today confirmed...

12 January 2021

New Art Installation Revealed at Chicago's Tallest Tower

EQ Office revealed Atmospheric wave wall, a new cultural landmark and the first public art installation in Chicago by globally acclaimed artist Olafur Eliasson. Prominently...

13 October 2020

Iconic Chicago Tower Bets on the Future of Co-Working

Reports of the demise of co-working during the pandemic are greatly exaggerated, if you ask the owner of Willis Tower. In a bet on the...

25 September 2020

New Partnership Brings Renewable Energy to Chicago Landmark Tower

Dynegy today announced that it has entered into a multi-year partnership with Chicago's iconic Willis Tower to provide 100% renewable electricity to the Tower. "Sustainability...

18 July 2019

Transformation of Chicago’s Willis Tower Begins with New Art-Filled Lobby

EQ Office, the US office portfolio company owned by Blackstone, has reopened Willis Tower’s Wacker Drive lobby, featuring a new, one-of-a-kind art installation created by...

30 April 2019

Two Towers Progress onto Chicago’s Iconic Skyline

Vista Tower reached its final height on April 26 2019, when construction workers poured concrete to form the Chicago skyscraper’s 101st and final floor. That...

15 April 2019

New Architects Brought in for Manchester’s St. Michael’s Tower

Skidmore, Owings & Merrill (SOM) has been brought in to deliver Hodder + Partners’ controversial Saint Michael’s tower in Manchester, with the local practice kept...

23 January 2020

Join the CTBUH Chicago Future Leaders Committee for a tour of Gensler's downtown Chicago office space! The afternoon event will feature a short presentation on Gensler's current work.

28 August 2019

CTBUH Chicago led an illuminating tour of the wholesale renovation of the base of Willis Tower, the largest such construction project to take place since the building’s completion

28 August 2019

CTBUH Chicago led an illuminating tour of the wholesale renovation of the base of Willis Tower, the largest such construction project to take place since the building’s completion

11 July 2019

This special reception will give VIPs the opportunity to let loose in the fantastic setting of Willis Tower (formerly Sears Tower), Chicago’s current tallest building (442 meters).

2 May 2019

CTBUH Moment in History #4 discusses the controversial claim by the Petronas Towers for the title of “World’s Tallest Building” over the record holder at the time, Willis Tower.

28 March 2019

"CTBUH 50th Anniversary: Moments in History #3" explores the impact that CTBUH Chairman Fazlur R. Khan, partner, Skidmore Owings & Merrill, had on the tall building industry.

29 November 2018

Building Tall Lecture Addresses Skyscraper Renovations

The latest event in the Building Tall Lecture Series, hosted by the Chicago Architecture Center and CTBUH, featured a panel on revitalizing iconic skyscrapers.

1 February 2018

Fourth Building Tall Lecture Series: Greening Tall

The Chicago Architecture Foundation (CAF) and CTBUH hosted a panel discussion on the movement to incorporate green features into tall buildings.

7 December 2017

CTBUH Founder, Dr. Lynn Beedle, at 100

The founder of the CTBUH, Dr. Lynn Beedle, a professor and eventually director of the Fritz Engineering Laboratory at Lehigh University, would have been 100 years old on December 7.

13 October 2016

The Council is pleased to announce the Top Company Rankings for numerous disciplines as derived from the list of projects appearing in 100 of the World’s Tallest Buildings.