The Willis Tower which is considered as one of the finest locations for business in Chicago,is a multi-tenant office building with more than 100 different companies doing business there, including major law firms, insurance companies and financial services firms. It has a rentable floor area of 418,064 sq. m (353,961 sq. m) and a total of 104 elevators which includes 16 double-decker elevators.
Earthquake Safety :
Special Design Features :The design for the Willis Tower incorporates nine steel-unit square tubes in a 3 tube by 3 tube arrangement, with each tube having the footprint of 75 feet by 75 feet. The design allows future growth of extra height to the tower if wanted or needed.
Observation Decks :
The Sears Tower Skydeck observation deck on the 103rd floor of the tower is 412 m (1,353 ft)
Willis Tower remains the tallest building in the Americas, and retains the world record when measuring from sidewalk level of the main entrance to the top of the antenna. With a pinnacle height of 1730 feet (527 m), it is the second tallest freestanding structure in the Americas, as it is 86 feet (26 m) shorter than Toronto's CN Tower, and is the only other freestanding structure in the Americas to exceed 1640 feet (500 m) in height. As of August 2009, Willis Tower is the fifth tallest freestanding structure in the world (by pinnacle height), after the Burj Dubai, the Guangzhou TV & Sightseeing Tower, the CN Tower and the Ostankino Tower.
At 1,482.6 feet (451.9 m) tall, including decorative spires, the Petronas Twin Towers in Kuala Lumpur, Malaysia, laid claim to replacing the Sears Tower as the tallest building in the world in 1998. Not everyone agreed, and in the ensuing controversy four different categories of "tallest building" were created. Of these, Petronas was the tallest in one category (height to top of architectural elements, meaning spires but not antennas).
Taipei 101 in Taiwan claimed the record in three of the four categories in 2004 to become generally recognized as the tallest building in the world. Taipei 101 surpassed the Petronas Twin Towers in spire height and the Sears Tower in roof height; it also claimed the record for highest occupied floor. The Sears Tower retained one record: its antenna exceeded the Taipei 101's spire in height. In 2008, the Shanghai World Financial Center claimed the records of tallest building by roof and highest occupied floor.
On August 12, 2007, the Burj Dubai in Dubai, United Arab Emirates was reported by its developers to have surpassed the Sears Tower in all height categories.
When completed, 1 World Trade Center in New York City is expected to surpass Willis Tower through its structural and pinnacle heights, but not by roof or highest occupied floor. Burj Dubai, currently topped out but still under construction in Dubai, has laid claim (by a significant margin) to all height records, surpassing the Sears Tower, the CN Tower, 1 World Trade Center, Taipei 101 and Shanghai World Financial Center in every category. The Chicago Spire, which has a planned height of 610 m (2,000 ft) is expected to lay claim to all categories of height records in the Americas upon completion, but its construction is currently on hold due to financial difficulties.
Until 2000, the Sears Tower did not hold the record for the tallest building by pinnacle height. From 1969-1978, this record was held by the John Hancock Center, whose antenna reached a height of 1,500 ft (457.2 m), or 49 ft (14.8 m) taller than the Sears Tower's original height of 1,451 ft (442 m). In 1978, One World Trade Center became taller by pinnacle height due to the addition of a 359 ft (109.3 m) antenna, which brought its total height to 1,727 ft (526.8 m). In 1982, two antennas were installed on top of the Sears Tower which brought its total height to 1,707 ft (520.3 m), making it taller than the John Hancock Center but not One World Trade Center. However, the extension of the Sears Tower's western antenna in June 2000 to 1,730 feet (527 m) allowed it to claim the title of tallest building by pinnacle height.
