6. John Hancock Tower

Location: Boston, MA

Year of Fail: 1973

Once the tallest building in the U.S. outside of New York City, the 100-floor skyscraper built in 1968 won accolades from the architecture and design communities. That is, until an error in the window design caused 500-pound windowpanes to detach from the building and crash to the sidewalk hundreds of feet below. Police had to evacuate neighboring streets any time winds reached 45 MPH. In 1973, all 10,344 windowpanes were replaced at a cost of $5,000,000. During the repairs, sheets of plywood replaced empty windows of the building, earning it the nickname "Plywood Palace."

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