Today is the 115th anniversary of the Antikythera mechanism discovery celebrated on Google with a nice Doodle.

Antikythera mechanism is an ancient Greek analogue computer and orrery used to predict astronomical positions and eclipses. as well as a four-year cycle of athletic games that was similar, but not identical to, an Olympiad, the cycle of the ancient Olympic Games.

The device is a complex clockwork mechanism composed of at least 30 meshing bronze gears.

Further information

Article about the Antikythera mechanism in Wikipedia