The Antikythera mechanism is a bronze device with at least 37 interlocking gears capable of calculating the positions of the Sun and Moon, lunar phases, solar and lunar eclipses according to the Saros cycle (223 synodic months), and possibly the positions of the five planets known in antiquity. Recovered in 1900 from a shipwreck off Antikythera dated to around 60 BC, it was systematically studied from 2005 onward using high-resolution computed tomography as part of the Antikythera Mechanism Research Project. Its mechanical complexity has no documented parallel in the archaeological record until the mechanical astrolabes of the 10th century and the geared European clocks of the 14th century. Inscriptions on the mechanism itself link its calendar to the Corinthian system and suggest manufacture in Rhodes or within the astronomical circle of Posidonius. The historical canon of technology placed precision mechanics as a medieval achievement; the mechanism demonstrates that this capability existed in the Hellenistic world fourteen hundred years before its documented reappearance.