In 1900, a storm blew a boatload of sponge divers off course and forced them to take shelter by the tiny Mediterranean island of Antikythera. Diving the next day, they discovered a 2,000 year-old Greek shipwreck. Among the ship's cargo they hauled up was an unimpressive green lump of corroded bronze. Rusted remnants of gear wheels could be seen on its surface, suggesting some kind of intricate mechanism. The first X-ray studies confirmed that idea, but how it worked and what it was for puzzled scientists for decades. Recently, hi-tech imaging has revealed the extraordinary truth: this unique clockwork machine was the world's first computer.