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It's a piece of military aviation engineering so secretive that the people who built it were routinely subjected to lie-detector tests.
An employee who attempted to sell information about it spent nearly 20 years behind bars.
The B-2 stealth bomber is such an important piece of the US Air Force's artillery, one has never been publicly put on display long-term.
Close-up glimpses of the aircraft are carefully stage-managed.
When it was first publicly displayed in 1988, the Cold War era threat of espionage and remained so intense that guests were not even allowed to see the rear of the craft.