Antikythera mechanism, artwork. Side view (centre) and rear and front views (either side) of the antikythera mechanism, an early form of mechanical calculator found circa 1900 in a 1st-century BC Roman shipwreck. The views at right and left are see-through, showing the internal and external aspects. The smaller views at right show (from top): the original artefact recovered from the wreck, and an X-ray and diagram of the mechanism.