John Hancock Center - Chicago, Illinois - Wikipedia Entries on Waymarking.com

The John Hancock Center, 100 storey skyscraper in Chicago, is one of the most distinctive elements of stunning city' skyline and thanks to it's unique construction it's also important civil engineering landmark.

The John Hancock Center, one hundred storey skyscraper completed in 1969, has a remarkable design with the huge X-braces serving both a structural and a visual purpose. Visually, it gives the impression of stability and it moves the eye away from the human-sized windows. "Big John" was tallest building in Chicago (or anywhere outside New York) from 1969 to 1973. Including its new antennas (2002), the John Hancock Center has a height of 457 m, making it one of the tallest building in the world when measured to pinnacle height.

The construction was designed by the engineer Fazlur Khan and architect Bruce Graham from Skidmore, Owings & Merrill. Fazlur Khan devised the frame-tube system, which he also implemented in the Sears Tower. This new construction method was made possible by new technologies, like more advanced software and new developments in steel. Thanks to the new construction method, it was possible for Kahn to design constructions which could resist the strong windforces more effectively by having the forces absorbed by all three dimensions of the building. The diagonals are connected to the exterior columns, making if possible for the forces to be carried over from the braces to the columns and back. The innovative construction also resulted in a 50% decrease of required steel compared to skyscrapers built with interior columns.

The observation deck at the top of the John Hancock Center gives one of the best views you can have on the Loop, Chicago's downtown area. For more information about the observatory and for some great pictures taken from the John Hancock Center, jump to the website of the Hancock Observatory.

[taken partially from www.aviewoncities.com]