The Antikythera Mechanism is the oldest known mechanical calculator. It was constructed around the second century bce and
lost in a shipwreck very close to the small Greek island of Antikythera. The shipwreck was discovered 2,000 years later, in 1900. The Mechanism was recognized in the spring of 1902 as a geared mechanical device displaying calendars and astronomical information. Application of modern imaging methods to the surviving fragments has led to general agreement on the basic structure of the device and its solar and lunar astronomical functions. The reading of the remains of its extensive inscriptions
has shown that it was also intended to display the shifting position of the planets in the zodiac. In this review, we set out our view on what is known about the device, what can reasonably be conjectured and what major uncertainties still remain regarding its origin, context and purpose.