When they built the Hancock Tower—and it started falling apart

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It’s the tallest building in Boston, besting the Prudential Tower by 40 feet. Its 60 stories of gleaming windows that reflect the sky have become an iconic part of the city’s skyline. But the tower’s history isn’t as perfect as the reflection in its glass windows today.

The John Hancock Tower project was announced in 1967, two years after the Prudential Tower was dedicated a few blocks away, according The Boston Globe. Groundbreaking began in 1968, but the excavation was bungled and nearby Trinity Church was damaged. The church sued John Hancock and won $11.6 million, according to The Globe.

Then rumors started circulating that the tower was sinking, which Hancock’s representatives rebutted, according to a news report from 1972.

And then the windows, which weighed 500 pounds each, started popping out of the building during high winds while it was still under construction. The opening of building was delayed from 1971 to 1976, and the cost went from $75 million to $175 million, according to The Globe.

The window issue persisted for four years, according to The Globe. It was discovered that the cause was in the design of the window, so all 10,334 panes of glass had to be replaced.

Then it was discovered that the tower swayed to a dangerous degree. The tower required “interior reinforcing to prevent walls and partitions from cracking in high winds,’’ according to a Globe article from March 1975.

Finally, on September 29, 1976, the new addition to the city skyline was dedicated. It went on to be awarded the American Institute of Architects’ National Honor Award in 1977. The building was designed by noted architect I.M. Pei, who also designed Boston’s Government Center and the John F. Kennedy Presidential Library & Museum.