When was sears tower chicago built

The building slowly stretched to 4. As designed by architect Bruce Graham and engineer Fazlur Khan of the Chicago office of Skidmore Owings and Merrill SOM , the structure was a "bundled tube" system of nine squares with sides of 75 feet for an overall x ft , sheathed in a curtain wall of dark tinted glass. Above the fiftieth floor, some squares dropped away as the tower rose to create smaller floor plates and a distinctive stepped silhouette. The Tower is fronted by a separate tourist entrance, the Skydeck Pavilion added in by Skidmore Owings and Merrill.

Following a gradual decline in prosperity during the s, Sears decided to sell the tower in In , Sears transferred effective control of the tower to its two creditors and vacated the premises by the following year.

In order to build the tower, Sears purchased 15 buildings from owners. But more problematic was Quincy Street, which divided the lots the building was going to go up on.

Unlike fellow giants like the Empire State Building and the World Trade Center, the Sears Tower was actually constructed as a collection of nine separate buildings, planted together in a unifying square.

Khan was particularly uncertain that the tube system would yield a sleek-looking skyscraper. As the story goes, during a lunch to discuss these reservations, Graham grabbed a handful of Camel cigarettes from his pocket and displayed the bundled cylinders, each peering out of his fist at different heights, to his partner.

The Willis Tower laid the foundation for the supertall buildings being built today. Architects have always been tasked with designing tall buildings to resist wind loads. But as buildings continued to grow taller and taller, new solutions were required. Their use of the innovative system ushered in a whole new era of skyscrapers.

The tower is comprised of a cluster of nine tubes connected together to act as a single unit. The tubes support one another, strengthening the structure as a whole. Meanwhile, the variations in tube height disrupt the force of the wind.

In , Sears Roebuck and Company was the world's largest retailer, employing approximately , people across Chicago. In order to consolidate current staff and accommodate anticipated growth, the company hired SOM to design a three million-square-foot office tower. The location of the tower was strategically selected for its proximity to expressways and commuter rail lines to benefit Sears employees. The inhabitants of the bustling office building generated new energy in a formerly stagnant West Loop neighborhood.

In , the London-based insurance broker Willis Group Holdings leased more than , square feet of office space on three floors of the Sears Tower. Their contract included naming rights for 15 years. On July 16, , the name of the building was officially changed to Willis Tower.