Chicago, United States · Completed 1974
| Location | Chicago, United States |
|---|---|
| Completed | 1974 |
| Height | 442 m |
| Floors | 108 |
| Use | Office |
| Structure | Steel (leed gold o+m: existing buildings) |
| Developer |
The Blackstone Group L.P.) |
|---|---|
| Architect |
Skidmore, Owings & Merrill (SOM) Gensler |
| Structural engineer |
Skidmore, Owings & Merrill (SOM) |
| Other consultants |
Jaros Baum & Bolles Enclos Corp. Morse Diesel International EQ Office |
Willis Tower, Chicago. The tower's structure comprises nine squared tubes, each rigid within itself without internal supports. The tubes are bundled together as a closed square below the first 50 stories. Above the first 50 stories, the tubes terminate at varying heights and create a multi-tiered form. The structural steel frame was pre-assembled in sections and then bolted into place on site. The lightweight building skin, a black aluminum and bronze-tinted glare-reducing glass, serves as an insulator between the interior and exterior structure in order to maintain a relatively constant temperature, which minimizes the expansion and contraction of the frame. [SOM] [Top of screenshot cut — likes count not visible.]