"The Antikythera mechanism, one more mystery of the ancient world, is an ancient mechanical calculator (also described as the first known mechanical computer) designed to calculate astronomical positions. It was recovered in 1900-01 from the Antikythera wreck, but its complexity and significance were not understood until decades later. It is now thought to have been built about 100-150 BC. This was some one-and-a-half thousand years before mechanisms of such complexity had been invented. Technological artifacts of similar complexity did not reappear until the 14th century, when mechanical astronomical clocks appeared in Europe."