Descend into history, 75 feet underground. The Diefenbunker is a once-top secret, four-storey underground bunker, originally designed as the centre for Canada’s defence against nuclear attack during the Cold War. It is now a one-of-a-kind museum and national historic site, offering unique and immersive experiences for visitors year-round. Each admission pass can be redeemed for one-time general admission (a guided or self-guided tour) to the Diefenbunker.