The building was originally named Sears Tower.This all-glass structure allows visitors to stand on top of transparent glass and look down, getting a feeling of being in the air. A stunning feature of the Sky-deck is the glass balcony. More than 1.5 million people visit the Sky-deck every year. The structural design of the building allows it to sway in high wind conditions – and visitors can experience this extraordinary phenomenon at the observation deck. At a height of 1353 feet, it offers a stunning and sweeping view of the city. One of the notable features of the Willis Tower is its observation deck, known as the Sky-deck. The building houses around 104 elevators. Together with the antennas installed at the top, the building’s height is 1729 feet. It stands 442 meters of around 1450 feet tall. The building has a total of 110 floors with 3 basement floors. This structure gives Willis Tower its iconic ascending shape. From 90th to 180th floors, two tubes remain.

The tube-like structures enabled Khan and SOM architects to ensure structural integrity of a building of exceptional height.Īs the building rises up, the external tubes terminate and only the core tubes continue. The nine tubes rise concurrently up all the way to the 50th floor. It essentially comprises of 9 tubes, designed in a 3 x 3 matrix. The Willis Tower is among the first buildings to make use of ‘tubes’. And he was instrumental in crafting a unique and defining outlook for the building. Khan was the main structural engineer involved in the project. One of the key figures involved in the planning and construction of the Willis Tower was Fazlur Rahman Khan. Skidmore, Owings & Merill were selected as the architects for the building. In order to consolidate them in one place, the Sears Tower was conceived. At the name, Sears had a large number of employees in the Chicago area. The tower was originally named the Sears Tower, after the retailer of the same name.

Planning for the Willis Tower began as early as 1969. The building is known for its bronze-tinted and black aluminum glass exterior. It once held the distinction of being the tallest building in the world and is today among the top 20 tallest buildings around the globe. Willis Tower is a skyscraper located in Chicago, Illinois.

Sears tower located