For a quarter of a century, the Sears Tower in Chicago was the tallest building in the world. It remains today as an instantly-recognizable landmark on the city skyline.
In 1969, the Sears Company needed a new building. From its beginnings as a tiny mail-order business, Sears and Roebuck had grown into the largest retail chain store in the world, with almost $9 billion in annual sales and over 350,000 employees. Some 13,000 of these were administrative, spread out in seven regional centers around the country, and the company decided that it wanted to consolidate them all into one office building to be located in Chicago (both because of the city’s central location and because Chicago was Sears’ home town). Local architectural firm Skidmore, Owings and Merrill was given the job of designing a new building.
SOM had recently finished its work on the 100-story John Hancock Center. This building used a new method of construction called a “trussed tube”, in which the primary support for the structure came from the outer walls rather than from an internal frame. Now, the firm was ready to try out a “bundled tube” style of construction, in which several of these trussed tubes would be contained together inside an outer skin–like crayons in a box. This design presented several advantages: it used the minimum amount of construction material for any given volume, it allowed more interior space with fewer internal columns and walls, and it gave great lateral strength–important for withstanding Chicago’s famously strong winds.
The original design for the “Sears Tower” called for 70 floors. When Sears decided to add extra office space that could be rented out, the project expanded to 110 stories, which would make it the tallest building in the world. Fifteen hollow tubes were intended to be built, but when plans for a hotel to occupy a large portion of the structure were dropped, the design was cut back to just nine tubes, each measuring about 75 feet square. Two of these ended at the 50th floor, two more stopped at the 66th floor, and three more at the 99th, leaving the final two tubes to extend to the full height of 110 stories. The outside of the Tower would be sheathed with tinted-glass windows and anodized aluminum. A “Skydeck” would be installed on the 103rd floor to give visitors a birds-eye view of the city.
Construction began in 1970 and continued for three years, until the Sears Tower was opened in May 1973. At a height of 1450 feet, it became the tallest building in the world, beating out the former record-holder–the World Trade Center Twin Towers–by 83 feet.
The building was an architectural marvel and quickly became a Chicago landmark. For Sears, however, the joy was short-lived. The company was crippled by declining sales, and in 1993, to cut costs, Sears sold the Tower and moved its offices into a smaller building. After that, the Tower was sold several more times, but because no other large company had moved in, it kept the name “Sears Tower”.
Meanwhile, the Petronas Tower opened in Kuala Lampur, Malaysia, and claimed the title of “the tallest building in the world”, sparking off a debate among purists. The official height of the Petronas Tower included the antenna spires on the roof, while that of the Sears Tower did not. And so, some devotees maintained, the Chicago skyscraper was still the world’s tallest building. The argument ended in 2001 when the Taipei 101 Tower opened in Taiwan, which was taller than both–but the debate began anew when One World Trade Center, with its lofty spire, opened in New York in 2013 and claimed to be the tallest building in the US. As a result, there are now two different recognized categories of “height” records–one for buildings with spires, and one without. And so the Sears Tower is still recognized as the tallest building in the US from ground to roof.
Then in 2009, the British insurance company Willis Group moved its 500 administrators into the Sears Tower and, claiming naming rights, re-christened it the “Willis Tower”. Once again, argument ensued, with petitions appearing to protest against the name change. To this day, many Chicagoans still stubbornly refuse the new name and continue to refer to the building as the “Sears Tower”.
Shortly after the name change, the Skydeck became the center of a renovation which added a visitor’s center and four retractable glass boxes extending out over the side of the building, known as “The Ledge”, which give an unobstructed view in all directions, including straight down. Today, about 1.5 million tourists visit the Sears Tower and its observation deck each year.