The Antikythera mechanism (/ˌæntɨkɨˈθɪərə/ ANT-i-ki-THEER-ə or /ˌæntɨˈkɪθərə/ ANT-i-KITH-ə-rə) 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 but, 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.
More information on the Wikipedia page , which has information on the Antikythera Mechanism Research Project and various papers on the device. Some information here . The Smithsonian page is .