Burj Khalifa with Smith's attempts to make the crown more slender. The building opened on 4 January 2010. The tower was designed by Skidmore, Owings and Merrill (SOM), which also designed the Willis Tower (formerly the Sears Tower) in Chicago and the One World Trade Center in New York City. Burj Khalifa uses the bundled tube design of the Willis Tower, invented by Fazlur Rahman Khan. Due to its tubular system, proportionally only half the amount of steel was used in the construction, compared to the Empire State Building. Khan's contributions to the design of tall buildings have had a profound impact
Vista Tower (Chicago) Vista Tower (Chicago) Construction started in August 2016 with expected completion in 2020. Upon completion, it will become the city's third-tallest building at . Designed by a team led by architect Jeanne Gang, Vista will supplant the nearby Aqua skyscraper (also designed by a team led by Jean Gang) as the tallest structure in the world designed by a woman. This will make Chicago home to the two tallest structures designed by a woman. Vista Tower is a joint project of Magellan Development Group and Wanda Group. The original estimated cost of construction was $900 million. The building will have