- Structural engineer Fazlur Rahman Khan]]> Image 4: https://www.som.com/projects/the-ledge-at-skydeck-chicago/]]> - 1971 Excavation of cite starts.
- 1972 steel frames start being implemented and put in place.
- 1973 Mechanical, Electrical, interior work, & windows are implemented.
- May 3, 1973 construction finished.
- Opened September 1973 to the public. ]]> Image 4: Creative comments]]> - 110 floors with 45,000 sq ft average per floor.
- Top 25 tallest buildings in the world.]]> -Concrete.
-Glass.
-Aluminum.
-Marble.
-Wood.]]>
- Skidmore, Owings & Merrill. “The Ledge at Skydeck Chicago.” Last modified 2009. https://www.som.com/projects/the-ledge-at-skydeck-chicago/.]]>