In 1959, Canadien Prime Minister John Diefenbaker commissioned the Diefenbunker in case of a Soviet nuclear strike during an era of rising Cold War tensions. The bunker was constructed outside of Ottawa in less than 18 months. The Diefenbunker could house up to 535 people for 30 days, and it was supposed to protect Canada’s leading government officials following a nuclear attack. After 32 years in operation, the Canadian government retired the Diefenbunker in 1994 after the Cold War ended. It was declared a historical site the same year.