Willis Tower
Willis Tower is a 110-story, 1,451-foot (442.3 m) skyscraper in Chicago's Loop district. When it was completed in 1973, it was the tallest building in the world — a title it held for nearly a quarter-century. Designed by architect Bruce Graham and structural engineer Fazlur Rahman Khan at SOM, its black glass and anodized-aluminum exterior is shaped by nine bundled square tubes arranged in a 3×3 grid that step back in stages as the tower rises. The lower floors served as the global headquarters of Sears — then the world's largest retailer — until 1994; the building was renamed in 2009 when Willis Group signed a lease, though Chicagoans still call it the Sears Tower. More than 1.7 million visitors a year ride up to the Skydeck, the highest observation deck in the United States — but the details worth lingering over are hidden in the glass ledges, the bundled-tube setbacks, and the elevator shafts.
United States · 7 The overlooked corners inside
The overlooked corners inside
Skydeck
The elevator takes about sixty seconds to reach the 103rd floor, fast enough that you feel a small pop in your ears from the pressure change. At 1,353 feet (412.4 m), the Skydeck is the highest observation deck in the United States and one of Chicago's most-visited attractions. On a clear day, you can see past the flat farmland of Illinois and across Lake Michigan to Indiana, Michigan, and Wisconsin. When the wind is up, you can feel the whole building shift slightly underfoot.
Sources: en.wikipedia.org
The Ledge
Cantilevered from the south-facing exterior wall of the 103rd floor, directly above South Wacker Drive, are a row of all-glass balconies that extend roughly 4 feet (1.2 m) beyond the facade. Informally known as the Ledge, they put you on a glass floor with an unobstructed view straight down to the street far below. Each box supports up to 5 short tons (4.5 metric tons) and has been open to the public since July 2, 2009.
Sources: en.wikipedia.org
In the Heart of this Infinite Particle of Galactic Dust
Step into the Wacker Drive lobby and look up: more than seven thousand translucent discs made of washi paper and resin hang from the ceiling in a dense, still cloud that fills the entire overhead expanse. The piece is *In the Heart of this Infinite Particle of Galactic Dust*, created by artist Jacob Hashimoto in 2019. Light passes through the gossamer discs and scatters in shifting patterns across the surrounding walls — a rare moment of pause inside what is otherwise the building's busiest threshold.
Sources: en.wikipedia.org
Color Factory
Two floors below the lobby, tucked inside the Catalog shopping concourse, is a space that feels nothing like the steel tower above it: Color Factory, a 24,000-square-foot interactive color experience and the brand's largest flagship, which opened in August 2022. Its ten rooms were painted in 117 different colors; one of them holds a ball pit of 200,000 balls in shades of green, spread across roughly 2,600 square feet and served by two slides. Artists Camille Walala, Liz West, Edra Soto, and Yuri Suzuki contributed installations, alongside partners MCA Chicago, local literacy nonprofit 826CHI, and SocialWorks. Each room draws on Chicago imagery — from the blue-and-white stripes of the city flag to the sport pepper on a Chicago-style hot dog.
Sources: rejournals.com · colorfactory.co
Bundled-Tube Structure and Facade
Looking up from the street, Willis Tower doesn't taper like a spire — it steps back in distinct stages, each one revealing the bundled-tube system at the heart of its structure. The building is made up of nine square tubes, each 23 by 23 meters, that terminate at different heights: the full nine are present up through the 50th floor (roughly 4,800 m² per floor); two tubes on the northwest and southeast drop off at the 50th floor, two more on the northeast and southwest at the 66th, leaving a cross-shaped five-tube arrangement through the 90th floor; above the 90th, only the west tube and the center tube continue to the 108th floor, shrinking each floor to about 1,141 m². The exterior is anodized aluminum and black glass, with 16,000 rectangular windows — each approximately 1.5 by 2.4 meters — set with bronze-tinted glass.
Sources: en.wikipedia.org
Structure and Building Systems
The numbers behind Willis Tower are striking: 67,000 metric tons of steel, roughly 800 met… 🔒 Unlock the full guide
Sources: en.wikipedia.org
Elevators and Escalators
Willis Tower has 103 elevators, 14 of which are double-deck cars; all told, 97 cabs serve… 🔒 Unlock the full guide
Sources: en.wikipedia.org
FAQ
What overlooked corners are worth seeing inside Willis Tower?
Skydeck, The Ledge, In the Heart of this Infinite Particle of Galactic Dust and more — 7 spots in all, each with sources and a guide in your language to read or listen to on the spot.
Is the Willis Tower guide free?
The first 5 spots are free to read; the other 2 unlock with a one-time purchase (not a subscription).