The Antikythera mechanism is an ancient Greek hand-powered orrery, described as the oldest example of an analogue computer, used to predict astronomical positions and eclipses decades in advance.
It could also be used to track the four-year cycle of athletic games which was similar to an Olympiad, the cycle of the ancient Olympic Games.
It was recovered in 1900–01 from the Antikythera wreck, a shipwreck off the Greek island of Antikythera.
The instrument has been designed and constructed by Greek scientists and dated between 150 to 100 BC. Technological artefacts approaching its complexity and workmanship did not appear again until the 14th century, when mechanical astronomical clocks began to be built in Western Europe.