In 1901, sea divers, exploring the wreckage of a Roman ship from 60-70 B.C. near the Greek Island Antikytheros, found a mysterious 2200-year-old bronze device, roughly the size of a large cereal box. Scientists studied the device for decades. Finally, they realized what it was.
An analog computer.
The Antikythera mechanism used over 30 meshing gears to make calculations with the precision of a master-crafted Swiss watch, based on astronomical and mathematical principles developed by the ancient Greeks. It could track the movements of the sun and moon through the zodiac, predict eclipses years in advance, and even model the moon’s irregular orbit. As a bonus, it showed the amount of time left until the next Olympic games!
This device is easily the most advanced technological artifact of the pre-Christian era. Unfortunately, the knowledge that made it possible was lost in antiquity and no machine of comparable complexity would appear for more than a thousand years until the giant mechanical clocks of 14th century Europe.
We know the Anitkythera mechanism is Greek because of the inscriptions found on many of its parts. Most scientists believe several such devices were built. No one knows the name of the mechanism’s inventor, or why it was on board a Roman ship. Perhaps it was being transported to Rome along with other spoils of conquest.