Boeing 747

The largest passenger airliner? yet built (though the planned [Airbus A3XX]? will be larger), the four-engined 747 combines a passenger-carrying capacities of up to 450 people with its unique two-deck configuration (the small upper deck is usually used for business-class passengers), with high-subsonic speeds and intercontinental range, in some configurations sufficient to fly Sydney-London non-stop (though no airline schedules such long routes).

Stuff needed:

• When was it first introduced?
• Variations, production history.
• Notable variations (Air Force One, Space Shuttle carrier. . . others?)