US Air Force/Tech. Sgt. Anthony Nelson Jr The original U-2, developed in complete secrecy, took its first flight in August 1955. Sixty-four years later, the Dragon Lady is still prowling the skies, but with a whole new set of controls and sensors. Visit Business Insider's homepage for more stories. Since the mid-1950s, the US Air Force's U-2 Dragon Lady has been cruising the upper reaches of the atmosphere, snooping almost totally unnoticed. While the mission is pretty much the same, the aircraft doing it are much different.See the rest of the story at Business InsiderNOW WATCH: The U-2 spy plane is so hard to fly pilots have to perform a 'controlled crash' just to land itSee Also:Share your opinion — become a BI Insider!36 things you should never say to your bossOne of America's oldest bombers just took flight with the Air Force's newest hypersonic weapon for the first timeSEE ALSO: The Air Force targeted its own personnel to see if they could 'recognize and thwart' cyberattacks