Fazlur Rahman Khan in the context of Structural engineer

In structural engineering, the tube is a system where, to resist lateral loads (wind, seismic, impact), a building is designed to act like a hollow cylinder, cantilevered perpendicular to the ground. This system was introduced by Fazlur Rahman Khan while at the architectural firm Skidmore, Owings & Merrill (SOM), in their Chicago office. The first example of the tube's use is the 43-story Khan-designed DeWitt-Chestnut Apartment Building, since renamed Plaza on DeWitt, in Chicago, Illinois, finished in 1966.

The system can be built using steel, concrete, or composite construction (the discrete use of both steel and concrete). It can be used for office, apartment, and mixed-use buildings. Most buildings of over 40 stories built since the 1960s are of this structural type.

The Willis Tower, formerly and still commonly referred to as the Sears Tower, is a 110-story, 1,451-foot (442.3 m) skyscraper in the Loop community area of Chicago in Illinois, United States. Designed by architect Bruce Graham and engineer Fazlur Rahman Khan of Skidmore, Owings & Merrill (SOM), it opened in 1973 as the world's tallest building, a title that it held for nearly 25 years. It is the third-tallest building in the Western Hemisphere, as well as the 23rd-tallest in the world. Each year, more than 1.7 million people visit the Skydeck, the highest observation deck in the United States, making it one of Chicago's most popular tourist destinations. Due to its height and location, the tower is visible from a great distance. The building has appeared in numerous films and television shows set in Chicago.

The building occupies a site bound by Franklin Street, Jackson Boulevard, Wacker Drive, and Adams Street. Graham and Khan designed the building as nine square "tubes", clustered in a 3×3 matrix; seven of the tubes set back at upper floors. The tower has 108 stories as counted by standard methods, though the building's owners count the main roof as 109 and the mechanical penthouse roof as 110. The facade is made of anodized aluminum and black glass. The base of the building contains a retail complex known as the Catalog. The lower half of the tower was originally occupied by retail company Sears, which had its headquarters there until 1994, while the upper stories were rented out.

875 North Michigan Avenue (formerly known as and still commonly referred to as the John Hancock Center) is a 100-story, 1,128-foot-tall (344-meter) supertall skyscraper located in Chicago, Illinois. Located in the Magnificent Mile district, the building was designed by Peruvian-American chief designer Bruce Graham and Bangladeshi-American structural engineer Fazlur Rahman Khan of Skidmore, Owings and Merrill (SOM). When the building topped out on May 6, 1968, it was the second-tallest building in the world after the Empire State Building, in New York City, and the tallest in Chicago. It is currently the fifth-tallest building in Chicago and the fourteenth-tallest in the United States, behind the Aon Center in Chicago and ahead of the Comcast Technology Center in Philadelphia. When measured to the top of its antenna masts, it stands at 1,500 feet (457 m).

The building is home to several offices and restaurants, as well as about 700 condominiums; at the time of its completion, it contained the highest residence in the world. The building was originally named for John Hancock Mutual Life Insurance Company, a developer and original tenant of the building, which itself was named for the U.S. Founding Father John Hancock. In 2018, John Hancock Insurance, years after leaving the building, requested that its name be removed; the owner is seeking another naming rights deal.

The Plaza on DeWitt is a 407 unit condominium property at 260 E. Chestnut Street in the Streeterville neighborhood of Chicago.

It was the first building in the world to implement the tubular construction, later used for the World Trade Center. Originally called the DeWitt-Chestnut Apartment Building, it was designed by Bangladeshi-American engineer Fazlur Rahman Khan while he was working for Skidmore, Owings & Merrill. It was completed in 1966 as a residential apartment building, and was converted to condominiums in 1975. The 43-story tower accommodates 407 residences and is clad in travertine marble. On the ground floor, French bistro Le Petit Paris serves traditional French cuisine.