Construction of the Diefenbunker. "A recently declassified film, Nuclear Roof depicts the design and construction of Canada's secret nuclear bunker, engineered to house the federal government in the occurrence of a nuclear attack. Built in secrecy during a 14 month period between 1959 and 1961, the facility became active in 1962 and operated 24 hours a day, 7 days a week, 52 weeks a year for over 33 years. This fascinating engineering feat, now a museum, is open to the public. Take a rare look at how it all began..."