How a simple pack of cigarettes inspired the world's most famous bundled skyscraper

Design · Published 30 September 2026 Swipe more like this →

In short: When architects needed to design a massive headquarters for a retail giant, they struggled to balance large floor plates with tenant needs. The solution arrived during a meeting when a designer staggered nine cigarettes vertically, creating the iconic, tapering tube structure that defined the Chicago skyline for decades.

In 1969, Sears was the world's largest retailer, employing 350,000 people. To consolidate its scattered Chicago workforce, the company commissioned Skidmore, Owings & Merrill to design a massive new headquarters. The project faced a unique architectural challenge: Sears required expansive lower floors for its own operations, but such large footprints were unattractive to potential commercial tenants who would occupy the upper levels.

Architect Bruce Graham and engineer Fazlur Rahman Khan solved this by conceptualizing a 3x3 matrix of nine square tubes. By allowing these tubes to terminate at different heights, they created a series of setbacks that tapered the building as it rose. This 'bundled tube' design provided the structural stability needed for extreme height while offering smaller, more conventional office spaces on the higher stories. The design was famously finalized after the pair arranged cigarettes to visualize the vertical staggering of the tower's components.

Completed in 1973, the structure reached 1,451 feet and held the title of the world's tallest building for nearly 25 years. Its construction was a feat of engineering, requiring a slurry wall foundation and temporary generators capable of producing 14,000 kilowatts to heat steel beams during winter. Despite its prestige, the tower struggled with occupancy during the 1980s office surplus and faced significant public opposition regarding potential television signal interference.

The building was renamed the Willis Tower in 2009 after the Willis Group acquired naming rights. Over the decades, it has undergone multiple ownership changes and extensive renovations, including the 2017 addition of the Catalog, a commercial complex designed by Gensler. Today, it remains a central fixture of the Chicago Loop, serving as a testament to the innovative structural engineering that allowed skyscrapers to reach unprecedented heights.

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