While proper testing and engineering can save developers millions of dollars, costs can shoot up incredibly if serious faults aren't detected before the construction phase. One of the best examples of what can go wrong with a high-rise is the 60-storey John Hancock Building in Boston. Designed by Harry Cobb and I.M. Pei - of Bank of China building fame - in 1968, the structure was beset with engineering problems from the start. Even before the skyscraper was finished, enormous panes of glass would fall off in high winds. It earned the nickname 'the Plywood Palace' because so many of its windows were boarded up. Theorists said the building was swaying too much in the wind, which was flexing the panes, causing them to pop out. This was not the case, although the structure did sway more than it should. A fault in the lead solder that bonded the double-glazed panes into their frames was eventually blamed for the problem. It was too rigid and did not allow the windows to move with the building. It took the replacement of all the skyscraper's 10,344 windows and US$7 million to fix the problem. The swaying was fixed by the installation of two 300-tonne counterweights on the structure's 58th floor at a cost of US$3 million. Then a Swedish engineer found that, in the event of extremely strong winds, the building was in danger of toppling over on its thin edge. It took 1,500 tonnes of bracing and a further US$5 million to fix that problem. In addition to the US$15 million spent on retroactively solving these problems, there were myriad costs associated with building delays. The building opened for business in 1976, four years after construction began, and it has since become one of Bostonians' favourite skyscrapers.