An infamous US Air Force high-altitude, single-seat, subsonic reconnaissance aircraft often used for spying directly over hostile territory, evading attack because of its high altitude (it cruises at above 70,000 feet).
Developed by Lockheed the aircraft was first flown secretly in 1955. It made its first over-flight of the Soviet Union in June 1956. The aircraft came to public attention when pilot Gary Powers was shot down over Soviet territory on May 1 1960. Variants of the U-2 continue operation today.
Physically, the U-2 looks like a glider, with a needle-like body and very long wings. It is also reportedly difficult to fly, as it is very easy to stall at its operating altitude. The cabin pressure is also so low that pilots must apparently wear a special rubberised suit to stop their blood boiling.