Antikythera Mechanism

In May 1902, a few lumps of corroded bronze from the Antikythera wreck were singled out at the National Archaeological Museum in Athens. They held gearwheels and lines of Greek text. Konstantinos Rados remarked at the time that only the inscriptions kept him from supposing the pieces came from a modern shipwreck.

The fragments survive as 82 pieces, about a third of the original machine, and hold 30 bronze gears. Fragment A, the largest, contains 27 of them. The museum's label counts seven large fragments, lettered A to G, and 75 small ones, and says it is not certain that all of the small pieces belong to the Mechanism.

The wreck

Sponge divers from Symi found the wreck by accident in 1900, at depths between 50 and 64 meters. With help from the Greek Royal Navy, they raised its cargo over 1900 and 1901: about 36 marble statues, the bronze statue known as the Youth, parts of a bronze "philosopher," and the fragments of the Mechanism. The museum says the wreck inaugurated underwater archaeology as a field of research. Valerios Stais, the museum's director, wrote in 1905 that the fragments came up late in the salvage.

Jacques-Yves Cousteau dove the site in 1959 and again in 1976, when his team brought up a small hoard of silver coins minted at Pergamon and Ephesos. None of the coins dates from after 58 BC, when that coinage was minted again. Together with the pottery, the coins put the sinking at about 60 BC, give or take 10 years. The museum wrote in 2016 that most of the cargo is still on the seabed.

What the machine did

In 2005, microfocus X-ray tomography and surface imaging at the museum read thousands of letters hidden inside the fragments, some of them 1.2 millimeters tall. The scans solved the back of the machine. It carried a calendar, a dial that predicted lunar and solar eclipses from Babylonian cycles, and a gear train that reproduced the moon's changing speed across the sky, following a theory Hipparchos worked out in the 2nd century BC.

A smaller dial tracked a four-year cycle of athletic games. It names the Olympic, Isthmian, Nemean, and Pythian games, along with two smaller festivals, the Naa at Dodona and the Halieia on Rhodes.

The calendar ring survives in six broken pieces. In 2024, Graham Woan and Joseph Bayley of the University of Glasgow used the positions of the surviving holes to estimate that the ring had 354 holes, one for each day of a lunar year. Their analysis found 354 hundreds of times more likely than 360.

The front

Much of the physical evidence for the front is lost, and its planetary display is known mainly from text. An inscription on the back cover describes the planets as "little spheres" on rings and the sun as a "little golden sphere." An inscription on the front cover lists the cycles of each planet, and in 2016 researchers read two numbers in it, 462 for Venus and 442 for Saturn.

On March 12, 2021, Tony Freeth and colleagues at University College London published a model of the front that turns those numbers into gear trains small enough for the space the surviving frame allows. The only piece of planetary gearing they could point to is a single gear with 63 teeth in Fragment D, which they reconstruct as part of a Venus train. The paper says, "Because of the loss of evidence, we cannot claim that our model is a replica of the original." It also adds a pointer for the moon's nodes, for which it says there is "no direct physical evidence."

Who made it, and when

The calendar dial uses the month names of a Corinthian calendar, which inscriptions place mainly in Corinth's colonies and in Epirus, in northwest Greece. The games dial includes the festival on Rhodes. Paul Iversen has proposed that the original design followed the calendar of Rhodes. Alexander Jones of New York University calls that "highly plausible" and reads the Corinthian months as an adjustment for an owner who lived where that calendar was used.

Cicero, in a book published in 45 BC, describes a sphere "recently" made by his friend Posidonius, whose turnings showed the sun, the moon, and the five planets moving as they do in the sky. The same passage mentions Archimedes. Such spheres were known in Cicero's day.

The date is contested. Jones writes that attempts before 2014 to date the letters or the calendar scale were inconclusive. The museum's label gives about 150 to 100 BC. In 2014, two separate studies placed the start of the eclipse dial's cycle in 205 BC, earlier than most proposed dates. Jones argues that a designer working as late as about 60 BC, the date of the wreck, could have chosen those 205 BC starting points.

A thousand years

The 2006 paper that reported the scans says the Mechanism "is technically more complex than any known device for at least a millennium afterwards." The next surviving geared instrument is a Byzantine sundial-calendar made between AD 400 and 600, now at the Science Museum in London. It has two gear wheels and a moon disc, and the Science Museum calls it the second oldest known of its kind. Nothing from the centuries between has been found.

The claims

Posts online call the Mechanism alien technology, or impossible for its time. Derek de Solla Price, who announced his first results on the fragments in 1958, compared the find to "opening a pyramid and finding an atomic bomb." Jones notes that television documentaries "have kept up this hyperbolic tradition."

The record ties the machine to known Greek and Babylonian work. The UCL team found that apart from Venus and Saturn, the planetary periods in its model "were already known in Babylonian astronomy," and it proposes a method, set out in Plato's Parmenides, by which Greek astronomers could have found the other two. The inscriptions use technical terms that appear elsewhere in only a handful of ancient authors, among them Ptolemy, Geminus, and Heron.

A few writers have argued that the fragments are a later fake. Jones notes that none of those arguments has passed peer review, and that photographs and written descriptions place the fragments in the museum from May 1902 onward.

In April 2025, Esteban Szigety and Gustavo Arenas posted a preprint, which they say "must be interpreted with caution," that simulated the gears using the tooth errors Mike Edmunds measured. With those errors, the gears would jam or disengage. They conclude that either the Mechanism never worked, or its real errors were smaller than the ones measured.

The Mechanism is displayed in Room 38, with other finds from the Antikythera wreck, in the bronze galleries at the northeast corner of the ground floor. The bronze Youth raised from the same wreck stands in Room 28 of the sculpture galleries.

Admission is 20 euros. Through November 15, 2026, the museum is open 8am to 8pm Wednesday through Monday and 1pm to 8pm on Tuesdays, with last entry at 7:30pm. Winter hours begin November 16 and have not been posted yet; last winter the museum closed at 3:30pm every day except Tuesday. It is closed on December 25 and 26, January 1, March 25, May 1, and Orthodox Easter Sunday.

Entry is free on the last weekend of September, on October 28, and on the 1st and 3rd Sundays of each month from November through March. It is also free for citizens of EU countries under 25 and for visitors from outside the EU under 18, with ID. Photography without flash is allowed. The nearest metro stations are Omonia and Victoria.