The Willis Tower (formerly the Sears Tower) is a 108-story, 1,450-foot (442.1 m) skyscraper in Chicago. The tower has 108 stories as counted by standard methods, though the building's owners count the main roof as 109 and the mechanical penthouse roof as 110. At completion in 1974, it surpassed the World Trade Center in New York City to become the tallest building in the world, a title that it held for nearly 25 years. It was also the tallest building in the Western Hemisphere for 41 years, until the One World Trade Center surpassed it in 2013, and had the highest occupiable floor until surpassed by the Central Park Tower in 2022. Willis Tower is considered a seminal achievement for engineer Fazlur Rahman KhanIt is currently the third-tallest building in the United States and the Western hemisphere – and the 23rd-tallest in the world. Each year, more than one million people visit its observation deck, the highest in the United States, making it one of Chicago's most popular tourist destinations. As of April 2018, the building's largest tenant is United Airlines, which moved its corporate headquarters from 77 West Wacker Drive (then the United Building) in 2012, occupying around 20 floors. Other major tenants include the building's namesake Willis Towers Watson and law firms Schiff Hardin and Seyfarth Shaw.[8] Morgan Stanley became the building's fourth-largest tenant in 2017 Known as the Sears Tower from its construction until the naming rights were included in a 2009 lease with the Willis Group, it served as the headquarters of retail company Sears from 1974 to 1994. Local area residents still refer to the building by its old name. In 1969, Sears, Roebuck & Co. was the largest retailer in the world, with about 350,000 employees Sears executives decided to consolidate the thousands of employees in offices distributed throughout the Chicago area into one building on the western edge of Chicago's Loop. Sears asked its outside counsel, Arnstein, Gluck, Weitzenfeld & Minow (now known as Arnstein & Lehr, LLP) to suggest a location. The firm consulted with local and federal authorities and the applicable law, then offered Sears two options: the Goose Island area northwest of downtown, and a two-block area bounded by Franklin Street on the east, Jackson Boulevard on the south, Wacker Drive on the west and Adams Street on the north, with Quincy Street running through the middle from east to west. After selection of the latter site, permits to vacate Quincy Street were obtained. Attorneys from the Arnstein firm, headed by Andrew Adsit, began buying the properties parcel by parcelSears purchased 15 old buildings from 100 owners and paid $2.7 million to the City of Chicago for the portion of Quincy Street the project absorbed Sears, which needed 3 million square feet (280,000 m2) of office space for its planned consolidation and predicted growth, commissioned architects Skidmore, Owings & Merrill (SOM). Their team of Colombian-Peruvian architect Bruce Graham and Bangladeshi-American structural engineer Fazlur Rahman Khan designed the building as nine square "tubes" (each essentially a separate building), clustered in a 3×3 matrix forming a square base with 225-foot (69 m) sides. All nine tubes would rise up to the 50th floor of the building, where the northwest and southeast tubes terminate. The northeast and southwest tubes reach the 66th floor; the north, east, and south tubes end at the 90th. The remaining west and center tubes reach 108 floors. The Sears Tower was the first building to use this innovative design. It was both structurally efficient and economic: at 1,450 feet, it provided more space and rose higher than the Empire State Building and cost much less per unit area. The system would prove highly influential in skyscraper construction and has been used in most supertall buildings since, including the world's current tallest building, the Burj Khalifa. To honor Khan's contributions, the Structural Engineers Association of Illinois commissioned a sculpture of him for the lobby of the Willis Tower.
| 1 | Builder | : | Skidmore, Owings and Merrill. | ||
|---|---|---|---|---|---|
| 2 | Old | : | 52 years old | ||
| 3 | material | : | black aluminum and bronze-tinted glass | ||
| 4 | Length | : | 1,450 feet | ||
| 5 | Height | : | 442 m, 527 m to tip | ||
| 6 | Width | : | 225 x 225 ft |
Pliny the Elder referred to Portus Delphini (Port of the Dolphin) as on the Ligurian coast between Genoa and the Gulf of Tigullio c In 1409 Portofino was sold to the Republic of Florence by Charles VI of France, but when the latter was ousted from Genoa the Florentines gave it back. In the 15th century it was a fief of families such as the Fieschi, Spinola, Adorno, and Doria. .
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