Willis Tower Overview

Willis Tower (Sears Tower)

• Willis Tower, formerly Sears Tower, is a prominent Chicago skyscraper, considered a symbol of the city.
• Architecturally, it stands out against the city's other impressive structures.
• Initial design differed from the final structure, initially planned as a series of large floors for Sears, but evolved into a taller, more vertical design to accommodate smaller tenants.
• Became the world's tallest building in 1973, holding the title for 23 years.
• Now recognised as 12th tallest in the world, second tallest in North America and the Western Hemisphere.
• Measurements for height include the highest occupied floor (1,431 ft.) and the top of the roof (1,450 ft) as defined by the Council on Tall Buildings and Urban Habitat.
• One of the world’s longest elevator rides, reaching the highest observation deck.
• Construction involved prefabricated steel sections, and extensive concrete use, requiring special elevators and on-site kitchens for workers.
• Building challenges included strong winds hindering work at high altitudes, and time considerations for meals, and high temperatures.

Early Sears Tower Beginnings

• Sears, Roebuck Co. was a highly influential corporation in the late 1960s, with considerable national influence (estimated at 1% of annual production).
• Chicago headquarters was envisioned as a massive structure to accommodate future growth of over 13000 employees.
• Initial design team comprised of architects Skidmore, Owings & Merrill (who designed the John Hancock Center) with Bruce Graham as lead architect.
• Fazlur Khan, a lauded structural engineer, became an iconic figure in the design and engineering process.

History of Skyscrapers

• Early skyscrapers stemmed from the rise of American businesses and the need for expansive office space, while staying near rail and port facilities.
• Innovations like the steel frame and safety elevators were crucial for building taller structures.
• The Monadnock Building (1891), one of the last buildings with load-bearing walls, showcased the evolution towards steel-based skyscrapers.
• Reaching higher floors was necessary to accommodate businesses, and elevators made taller buildings more practical.

First "Sears Tower"

• Sears' first national headquarters (1905) was a 12-story building in northwest Chicago.
• Initially a water tower, it later became a broadcasting studio for the company-owned radio station, WLS.
• The first Sears retail store opened near the tower complex.