In 1901, divers exploring a shipwreck off the coast of the Greek island Antikythera discovered a corroded lump of bronze that seemed out of place among the marble statues and pottery. It turned out to be one of the most significant archaeological finds of the 20th century: the Antikythera Mechanism.
Dating back to around 100 BC, this intricate system of over 30 meshing bronze gears was used by ancient Greeks to predict astronomical positions and eclipses for calendar and astrological purposes. It could track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games.
The complexity of the device suggests that Greek technology was far more advanced than previously thought. Nothing of similar complexity is known to have appeared for another thousand years, until the development of astronomical clocks in the 14th century. It stands as a testament to lost knowledge and human ingenuity.