The Antikythera mechanism recovered from a Roman shipwreck in 1901 turned out to be a hand-cranked bronze computer that could predict eclipses and track the irregular orbit of the Moon, and nothing of comparable mechanical complexity would appear anywhere on Earth for another 1,400 years. (opens in new tab)

Pulled from a Roman shipwreck in 1901, the Antikythera mechanism is a hand-cranked bronze calculator from the first century BCE whose gear-train sophistication would not reappear in the surviving record for another fourteen hundred years.