The Willis Tower, built as and still commonly referred to as Sears Tower, is a 108-story, 1,450-foot (442.1 m) skyscraper in Chicago. At completion in 1973, it surpassed the World Trade Center towers in New York to become the tallest building in the world, a title it held for nearly 25 years. The Willis Tower is the second-tallest building in the United States and the 14th-tallest in the world. More than one million people visit its observation deck each year, making it one of Chicago’s most popular tourist destinations. The structure was renamed in 2009 by the Willis Group as part of its lease on a portion of the tower’s space. The building’s official address is 233 South Wacker Drive, Chicago, Illinois 60606. 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: an area known as Goose Island 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. Sears, which needed 3,000,000 square feet (280,000 m2) of office space for its planned consolidation and predicted that growth would require yet more, commissioned architects Skidmore, Owings & Merrill (SOM) to produce a structure to be one of the largest office buildings in the world. Their team of architect Bruce Graham and 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. At the 50th floor, the northwest and southeast tubes end, and the remaining seven continue up. At the 66th floor, the northeast and the southwest tubes end. At the 90th floor, the north, east, and south tubes end. The remaining west and center tubes continue up to the 108th floor. Black bands appear on the tower around the 29th–32nd, 64th–65th, 88th–89th, and 104th–108th floors. These are louvres that allow ventilation for service equipment and obscure the structure’s belt trusses. Even though regulations did not require a fire sprinkler system, the building was equipped with one from the beginning. There are around 40,000 sprinkler heads in the building, installed at a cost of $4 million.
In February 2009, the owners announced they were considering a plan to paint the structure silver; this plan was later dropped. The paint would have “rebranded” the building and highlighted its advances in energy efficiency. The estimated cost was $50 million. Since 2007, the building owners have been considering building a hotel on the north side of Jackson, between Wacker and Franklin, at the plaza that is the entrance to the tower’s observation deck. The tower’s parking garage is beneath the plaza. Building owners say the second building was considered in the original design. The plan was eventually cancelled as city zoning does not permit construction of such a tall tower there. Although Sears’ naming rights expired in 2003, the building continued to be called the Sears Tower for several years. In March 2009, London-based insurance broker Willis Group Holdings agreed to lease a portion of the building, and obtained the building’s naming rights. On July 16, 2009, the building was officially renamed Willis Tower. On August 13, 2012, United Airlines announced it would move its corporate headquarters from 77 West Wacker Drive to Willis Tower. In 2015, the Blackstone Group completed purchase of the tower for a reported $1.3 billion, the highest price ever paid for a U.S. property outside New York City. The new owners are considering several plans for further site developments.
The Willis Tower observation deck, called the Skydeck, opened on June 22, 1974. Located on the 103rd floor of the tower, it is 1,353 feet (412.4 m) high and is one of the most famous tourist attractions in Chicago. Tourists can experience how the building sways on a windy day. They can see far over the plains of Illinois and across Lake Michigan to Indiana, Michigan and Wisconsin on a clear day. Elevators take tourists to the top in about 60 seconds, and allow tourists to feel the pressure change as they rise up. The Skydeck competes with the John Hancock Center‘s observation floor a mile and a half away, which is 323 feet (98.5 m) lower. Some 1.3 million tourists visit the Skydeck annually. A second Skydeck on the 99th floor is also used if the 103rd floor is closed. The tourist entrance can be found on the south side of the building along Jackson Boulevard.
In January 2009, Willis Tower’s owners began a major renovation of the Skydeck, including the installation of retractable glass balconies, which can be extended approximately 4 feet (1.2 m) from the facade of the 103rd floor, overlooking South Wacker Drive. The all-glass boxes, informally dubbed “The Ledge”, allow visitors to look through the glass floor to the street 1,353 feet (412 m) below. The boxes, which can bear 5 short tons (4.5 metric tons) of weight, opened to the public on July 2, 2009. However, on May 29, 2014, the laminated glass covering the floor of one of the glass boxes shattered while visitors were sitting on it, but caused no injuries. The broken glass was replaced within days, and tourist operations resumed as before.
