The five X's on each side go from floors 2-20, 21-37, 38-55, 56-74, and 75-91. A half-X extends from 92 to 97.
After engineer Fazlur Khan had calculated the tower's sway in high winds, no one knew the effect it would have on tenants. Lacking funds for a major psychological study, Khan improvised an experiment at Chicago's Museum of Science & Industry, placing 8 subjects on a rotating exhibit. The test confirmed that the sway would be within the limits of comfort.
The semicircular sunken plaza on the west side is a public oasis with seasonal plantings and a 12-foot waterfall.
Because of space constraints caused by the tower's tapering walls, common hallways and elevator lobbies are narrower on higher floors.
The top roof is almost exactly even with the 86th floor of the Willis Tower.
The idea of a tube-framed skyscraper was first realized two blocks down the street at The Plaza on Dewitt.
In 1988 the owners planned to cover the plaza with a gabled glass atrium extending to the lot line at Michigan Avenue. The proposal was shot down by extensive local opposition.
As happened later with the Sears Tower, the architects presented the developer with two options: either a pair of medium-height towers, or a single very large skyscraper.
As an alternative to balconies, about one-third of the residential units have "sky terraces" - a sort of tiled sunroom separated from living spaces by glass doors.
Since the floorplates do not transfer wind loads to the structural core as in most skyscrapers, it is possible to create a two-story space by cutting out the floor almost anywhere in the building.
The original sunken plaza on Michigan Avenue was larger and rectangular, and had a wide reflecting pool.
For the first few years of the building's existence there was a private restaurant in the skylobby called Club 44, for the exclusive use of residents and their guests. Its food was supplied by the public restaurant upstairs.
The base facade was originally clad in white travertine, but this was later replaced with a much darker granite. The black anodized aluminum facade starts at the second floor.
The alternative plan for the complex called for a 70-story apartment building and a 45-story office building of equal height, positioned at the northeast and southwest corners of the lot.
The office lobby was originally a high-ceilinged space on the second floor accessed by escalators. It was shifted to ground level in the 1990s, and the old space was converted to retail.
The outline of the John Hancock appears on the Illinois version of the quarter-dollar coin, minted in 2003.
The John Hancock Center was only the third building in the world to be taller than 1,000 feet tall and the first outside of New York. The first two were the Chrysler Building in 1930 and the Empire State Building in 1931.
America's highest indoor swimming pool is located on the 44th floor near the skylobby. The pool itself is carved out of the mechanical floor below.
The parking garage is accessed through a detached spiral ramp at the southeast corner; the double helix makes 3 loops each way between ground level and the garage.
The building tapers on all four sides, narrowing by a total of 105 feet on the east & west sides and 65 feet on the north & south.
Tallest building in Chicago (or anywhere outside New York) from 1969 to 1973; surpassed by the Standard Oil Building (now the Aon Center).
Remodeled in 1995, the lobby features rich travertine marble and textured limestone surfaces.
John Hancock Center is a member of the World Federation of Great Towers.
In order to fit the structural frame, the floors at the top of each X have extra-high ceilings (adding significantly to their property value).
The observation floor features the highest balcony in America, a screened-in area called the "Skywalk".
This was the first trussed-tube skyscraper ever built. The idea was developed by Fazlur Khan, based on a project of Illinois Institute of Technology graduate student Mikio Sasaki.
The slope of the windows helps to reduce the feeling of vertigo for people looking out of high floors.
The building is one of the most recognizable in the world and has won numerous awards for its distinctive style, including the 1970 Honor Award of the AIA Chicago Chapter.
The eastern antenna was elevated to its full height on Thursday, December 5th, 2002. The top of the antenna now reaches just higher than the roofline of the Sears Tower across town.
The maximum elevator speed is 549 m/min.
A band of white lights around the 100th floor is visible all over Chicago at night. The lights change color for Christmas, Valentine's Day, St. Patrick's Day, July 4, and Halloween.
In 1999 this building became the 30th recipient of the American Institute of Architects' prestigious Twenty-Five Year Award.
A segment of the east antenna was removed in 2000 when a broadcasting agency's lease terminated.
The building's distinctive X-bracing has made it an architectural icon, and increases the flexibility of interior spaces by eliminating the need for regular columns between the core and perimeter.
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