The Antikythera mechanism is an ancient analog computer designed to calculate astronomical positions.
It was recovered in 1900–1901 from the Antikythera wreck, but its significance and complexity were not understood until a century later. Jacques Cousteau visited the wreck in 1978. Although he found new dating evidence, he did not find any additional remains of the Antikythera mechanism. The construction has been dated to the early 1st century BC. Technological artifacts approaching its complexity and workmanship did not appear again until the 14th century AD, when mechanical astronomical clocks began to be built in Western Europe.
The device is just extraordinary, the only thing of its kind. The design is beautiful, the astronomy is exactly right. The way the mechanics are designed just makes your jaw drop. Whoever has done this has done it extremely carefully … in terms of historic and scarcity value, the mechanism is more valuable than the Mona Lisa.