The John Hancock Center is a 100-story, 1,127-foot (344 m) tall skyscraper, located at 875 North Michigan Avenue in the Streeterville area of Chicago, Illinois, United States. It was constructed under the supervision of Skidmore, Owings and Merrill, with chief designer Bruce Graham and structural engineer Fazlur Khan. When the building topped out on May 6, 1968, it was the tallest building in the world outside New York City. It is currently the fourth-tallest building in Chicago and the seventh-tallest in the United States (after One World Trade Center, the Willis Tower, the Trump Tower Chicago, the Empire State Building, the Bank of America Tower, and the Aon Center). When measured to the top of its antenna masts, it stands at 1,506 feet (459 m). The building is home to offices and restaurants, as well as about 700 condominiums, and contains the third highest residence (above adjacent ground level) in the world, after the Trump Tower (also in Chicago), and the Burj Khalifa (in Dubai). The building was named for John Hancock Mutual Life Insurance Company, a developer and original tenant of the building, and has the nickname "Big John".
The 95th floor has long been home to a restaurant, the latest tenant being "The Signature Room on the 95th Floor". Diners can look out at Chicago and Lake Michigan. The Observatory attraction (called "360 Chicago" since March 2014) competes with the Willis Tower's Skydeck across town. John Hancock Center is in the heart of Michigan Avenue, a prime tourist hotspot in Chicago, while the Willis Tower is in the financial district. John Hancock Observatory allows a 360° view of the city, up to four states, and a distance of over 80 miles (130 km). The Observatory has Chicago's only open-air SkyWalk and also features a free multimedia tour in six languages, narrated by actor David Schwimmer. The 44th-floor sky lobby features America's highest indoor swimming pool.
The project, which would at that time become the world's second tallest building, was originally conceived of and owned by Jerry Wolman in late 1964, the project being financed by John Hancock Mutual Life Insurance Co. Construction of the tower was interrupted in 1967 due to a flaw in an innovative engineering method used to pour concrete in stages that was discovered when the building was 20 stories high. The engineers were getting the same soil settlements for the 20 stories that had been built as what they had expected for the entire 99 stories. This forced the owner to stop development until the engineering problem could be resolved, and resulted in a credit crunch. This situation is similar to the one currently being experienced with the construction of Waterview Tower. The owner went bankrupt, which resulted in John Hancock taking over the project, which retained the original design, architect, engineer, and main contractor.
The building's first resident was Ray Heckla, the original building engineer, responsible for the residential floors from 44 to 92. Heckla moved his family in April 1969, before the building was completed.