The Willis Tower In 150 Years

Adapted, Demolished or Abandoned?
The answer has to do with the fate of Chicago in 2166.

Editor's note: This piece was produced in partnership with the Chicago Architecture Foundation, which provided research, expertise and other assistance during its development.

When Chicago was still celebrating the end of the Civil War, the city had a population of roughly 200,000 people. The most memorable structure from that era, the Water Tower, was still three years from construction. Today, 150 years later, the city’s population has grown by more than 1,200 percent, and the city’s tallest building, the Willis Tower, is more than 1,300 feet taller than the height of Chicago’s tallest building in 1866.

This is all to say a lot can change in 150 years. Which makes our question, from engineer Bill Muscat, pretty challenging:

What do we do in 150 years when our current buildings are too old? What do we do with an old Willis Tower?

Bill asked because he’s noticed that some of Chicago’s earliest skyscrapers — buildings he considers iconic — have been demolished recently. The first generation of skyscrapers is about 120 years old, so he picked a timeframe of 150 years, figuring that the Willis Tower would be pretty worn out by then. The tower was originally constructed in 1973 for the Sears Roebuck & Company headquarters, then renamed in 2009 by Willis Holding Group, who obtained naming rights as part of a lease agreement.

Bill’s question is based on the premise a building can become “too old.” That’s only partially true. The structural steel in a building like the Willis Tower could last for thousands of years, as long as it is climate-controlled and protected from the elements. The building’s cladding and systems (electricity, plumbing, HVAC) can certainly wear out, but they can also be maintained indefinitely, and even updated, as long as the building owners can afford it.

Bill’s question’s appealing because it gives all of us license to become amateur futurists, but in a focused way. As we reported an answer for Bill, we heard that when you think about the future of tall buildings in cities, it’s useful to consider why we build very tall buildings in the first place.

In 1900, architect Cass Gilbert famously described a skyscraper as a “machine that makes the land pay.” While tall buildings are certainly impacted by demand for space, client or city image, it’s economics that truly drives the construction of skyscrapers. Developers seek to maximize the rent that a single parcel generates. Urban districts with expensive land tend to have tall buildings, because those buildings have more floors, more square feet, and therefore, more revenue potential.

But calculations about whether a particular skyscraper “makes the land pay” are deeply entwined with the fate of the building’s immediate neighborhood, and the city in general. The building, its neighborhood and its city — each can change, and so can the relationships between them.

Nobody has a definitive answer to Bill’s question, because it depends so much on what happens to Chicago. But experts we spoke to agree there are three likely scenarios:

•The Willis Tower is maintained and adapted to suit the needs of Chicago in 2166.
•The Willis Tower is abandoned.
•The Willis Tower is demolished and replaced with another building.

Each scenario is possible, but each would require a very different version of downtown Chicago. We’ll explore each possibility and explain the relationship between the Willis Tower’s fate and that of Chicago in 2166.


In this scenario, Chicagoans want to be downtown: They don’t want long commutes, and they want to live and work near the lake, near parks and where the action is. A wide variety of amenities — parks, culture, schools, even hospitals — have made their way up into Chicago’s skyscrapers.

Architect Gordon Gill of the firm Adrian Smith + Gordon Gill Architecture likes this prospect:

“It would be amazing if [the Willis Tower] could be maintained and adapted over time. I think it’s a big enough building to take it. It’s got the scale of a small city.”

The glistening blue tower at 150 N. Riverside has been called "a building in a park" since it includes a green rooftop plaza and integrates with a new section of the Riverwalk. (Courtesy of Goettsch Partners)

The glistening blue tower at 150 N. Riverside has been called "a building in a park" since it includes a green rooftop plaza and integrates with a new section of the Riverwalk. (Courtesy of Goettsch Partners)

In 2009 Smith + Gill developed a plan to make the Willis Tower more sustainable. This “Greening Plan” proposed updates to the building’s mechanical systems, lighting, water, and exterior windows, along with new plans for renewable energy sources. Gordon Gill thinks in the future, photovoltaic glass panels could replace the windows, allowing the Willis Tower to not only generate its own power, but export electricity to other nearby buildings.

Urban economics play a role in bringing about this continuously renovated future Willis Tower. There is still enough demand to live or work in downtown Chicago, prompting the owners to rent the space out and make enough money to maintain and upgrade the building systems. There’s no reason to tear it down, since the real estate isn’t so valuable as to justify developing buildings twice or three times the height. There’s no reason to abandon a building that continues to generate revenue. The Willis Tower stays around because it’s still useful, or perhaps more accurately, it pays to continuously keep it useful.

Of course, if Chicago’s downtown becomes denser, street traffic could get even more congested. Gill suggests congestion could be eased if more transportation went vertical.

“If you had autonomous vehicles that could fly, you change the mobility of the grid,” he says. “If you arrive at the building, why do you have to arrive at the lobby? The lobby could be the 50th floor or 100th floor. Is there a personal vehicle that could come in through the window, dock the car in a bay, and then you go to work, or go home?”


How could this scenario happen? Phoebe Crisman, a Professor of Architecture at the University of Virginia, studies how cities change over time. She says large office towers in central business districts are sometimes abandoned. But for the Loop and the rest of downtown Chicago to empty out, she says we would have to “enter into a very serious economic decline.”

In the case of the Willis Tower, its future owners could no longer generate enough revenue in rent (or other sources) to pay for the high costs of maintenance. They could try to sell it, but it would be hard to find a buyer in a situation where its neighbors are clearing out. While it might be safer to demolish the building, Crisman says “The cost of demolishing a high rise building is huge."

"If the owner is strapped for cash and unable to make the building work financially, where is he or she going to get the money for demolition?”

Two similar 20th century examples include downtown Detroit and Johannesburg, South Africa. Both cities experienced shifting economies and racial strife downtown, after which major companies moved offices from downtown skyscrapers to other locations. They left for the outskirts of their respective cities or even to completely different regions. Many of Detroit's skyscrapers were abandoned or nearly abandoned for decades. (However, these things move in cycles, and some of those buildings are being redeveloped and occupied.)

Abandoned buildings--the David Broderick Tower looms behind the David Whitney Building in downtown Detroit. (Courtesy of Zachery Fein)

Abandoned buildings--the David Broderick Tower looms behind the David Whitney Building in downtown Detroit. (Courtesy of Zachery Fein)

This could happen in Chicago, but Crisman says central financial districts like the Loop tend to make minor migrations over long periods of time. North Michigan Avenue and the East Loop (the area north of Maggie Daley Park), are offshoots of the original Loop. But a big downtown like Chicago's almost never just vanishes unless something really traumatic happens.


In 2166, Chicago’s Loop is denser, more populous and more popular than ever, with apartments, offices, art, entertainment and parks sustaining an ever-increasing demand for home and office space in the Loop. To accommodate the demand (and make money), developers have filled all the available space with megatall buildings. The land the Willis Tower sits on is now so valuable that developers tear down the building to make space for a new, megatall building.

Author and illustrator David Macaulay writes books that explain architecture, cities and technology. He says Bill Muscat’s question for Curious City is an interesting one.

“A Chicago at twice the height than it is now … Willis and Hancock and so on all seem like little kids, and the old ones, the Tribune building and so on, they’re the toys, and they sort of put glass cases around them,” he says. “It’s entirely possible. Why not?”

If it sounds incredible, that may be because in 2016 the Willis Tower has been the tallest structure in Chicago for 42 years. Two generations have grown up knowing it to be the tallest building in the city. For its first 20 years, it was even the tallest building in the world. Now, it doesn’t even crack the top ten.

This is familiar territory for a Chicago architecture. Take the Board of Trade Building, for example. In the 1930s, it was a symbol of towering verticality at 600 feet. By 1965, it was no longer Chicago’s tallest, and only 9 years after that, it was dwarfed by the nearby Willis Tower. You can look down on the Board of Trade Building from the Willis Tower today, and despite its respectable 600 feet of height, and gleaming statue of Ceres, it looks dinky.

Think this scenario of a puny Willis Tower being demolished sounds far-fetched? Consider that Saudi Arabia’s Jeddah Tower, when complete in 2019, will be about twice the height of the Willis Tower. Architects agree there is no theoretical limit to the height of a skyscraper, and if we can build a 3,281 foot building today, think about what we might be able to accomplish in 2166. Maybe, somebody will get around to fulfilling Frank Lloyd Wright’s vision of The Illinois, a mile-high skyscraper.

Several year ago, Macaulay wrote a book called Unbuilding, which imagines a future in which the Empire State Building is purchased by a wealthy developer, carefully deconstructed, and packed up, with plans of reconstructing it in the Middle East. Although the book focuses on New York, Macaulay’s inspiration was actually the Willis Tower. He recalls watching a 1979 documentary that featured the architects of the (then) Sears Tower hypothesizing about deconstructing it someday. In Lewis Mumford: Toward Human Architecture, Mumford interviews other critics, architects, and historians on the impact of technology and progress on civilization.

But rather than simply hauling the demolished Willis Tower off to a landfill, Macaulay hypothesizes that by 2166, the steel in the Willis Tower may be valuable and reusable. He has an idea about taking the structural sections of the building — those nine square sections we can see bundled together as one tower, what architects call ‘tubes’ — and reusing them.

“If you take all the tubes apart, you have about 632 seventy-five foot square buildings,” Macaulay says. “It’s like the long sausage and you just cut it into slices. You have all these square buildings. Think of all the schools you could put into 75-by-75 foot squares made from floors of the individual tubes … if the structural steel was still good.”

His idea is intriguing because the Willis Tower’s massive steel frame structure is rare among skyscrapers today. The majority of tall buildings constructed around the world now are built with a reinforced concrete skeleton, making it nearly impossible to disassemble into pieces and reuse the structure. In the future, it’s possible that steel could become a rare commodity, and the Willis Tower a convenient source.

In Macaulay’s imagination, the Willis Tower could morph into an architectural organ donor for a future Chicago. In ancient Rome, this happened all the time. The Coliseum stone, for example, was reused to build other buildings in the city. It’s possible this could occur in Chicago someday too.

What's Next?

So which one is it?

Despite Bill Muscat’s initial assumption that the Willis Tower will be worn out in 150 years, the fate of the building has less to do with its building materials than what will happen to Chicago, and particularly to the Loop. Our experts agree: Economics and demand matter. If it pays to continuously use and adapt the Willis Tower, that will probably be what happens. If it pays to demolish it and build something bigger, that would happen. And if there’s nobody to pay — insufficient demand to justify maintaining the building — then it will likely be abandoned.

It was striking to us that all of our experts agreed on something else: The most likely scenario is one where the Willis Tower will be maintained and adapted. One reason is that it’s just easier to envision that future: Chicago isn’t really all that different than it is today, just denser. The sorts of transformations we would have to see that would lead to demolition or abandonment seem pretty far-fetched: Mega-tall buildings or an abandoned downtown. But 150 years is a long time. Back in 1866, today’s Chicago — with its buildings over 1,000 feet, an interstate highway system, a transit system with elevated and underground trains, jet airplanes constantly overhead, and without the stockyards — would be hard to imagine.

More about our sources

David Macaulay is a trained architect and published author. His newest book is The Way Things Work Now.

Phoebe Crisman is a Professor of Architecture at the University of Virginia, where she teaches design studios and lectures on architectural theory, urbanism and sustainability.

Gordon Gill is a Founding Partner at Adrian Smith + Gordon Gill Architecture. Additional expertise and advice from Dennis Rodkin, John Zils, Mark Sexton, and Judith Dupré.

More about our illustrator

Andrew Banks is an artist and freelance illustrator living on Chicago’s North Side. He works with pen and ink, watercolor, and graphite. His subject matter of choice is architecture, architectural landscapes and cityscapes. Banks creates artwork for clients ranging from architects and builders to educational institutions, non-profit organizations, event planners as well as individual clients seeking to commission original art. When he isn’t drawing or painting in his studio, Banks enjoys sketching on location throughout Chicago.

For full-size versions of the illustrations featured in this story:

· Abandonment
· Adaptation
· Demolition

About the questioner

Bill Muscat is an engineer. After asking this question and before Curious City started reporting an answer, he was hired by United Airlines, the largest tenant in the Willis Tower today. And that means Bill now works in the Willis Tower, which is fine with him. He likes Gordon Gill's scenario of the building being maintained and adapted, and he especially likes thinking about all the technology that might be employed to make the building suitable for future Chicagoans.

“I’d love for it to still be iconic,” he says. “Look at the Empire State Building or other cutting edge architecture in the world, these buildings that are still part of their city because they’re truly iconic and memorable. I think the Willis Tower is that to me. So I hope it’s still around.”

Bill is also intrigued by the third scenario in which the Willis Tower is demolished to make from for something else.

“Hopefully, the only reason it will be obsolete is that something else has replaced it, for the glory and beauty of Chicago, something else more iconic has been built.”

Jesse Dukes is Curious City’s Audio Producer. Jen Masengarb is Director of Interpretation and Research at the Chicago Architecture Foundation. Follow her @jmasengarb.

Correction: An earlier version of this story misstated who the current owners of the Willis Tower are, as of December 2016. The current owner is the Blackstone Group.

A clarification: Multiple readers pointed out that while many of Detroit's downtown skyscrapers were abandoned for decades, Detroit's downtown has become vibrant again, and may of those buildings have been, or are being, refurbished and reoccupied. This updated version of the story reflects this. Comments, questions or suggestions about this Curious City story or others are welcome at

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