The Antikythera Mechanism

In October 1900, sponge divers off the coast of the Greek island of Antikythera found this relic on the seabed.

For over half a century, scientists made little progress understanding what it was.  Today, with the use of modern technology and renewed scientific interest (papers published in Nature in 2006, 2008 and 2010) we know that the Antikythera Mechanism was built in Greece (possibly on the island of Rhodes) during the 1st century BC and was probably being transported to Rome when the ship it was on sunk.

The Mechanism is housed at the Greek National Archaeological Museum in Athens.  It's made of bronze, mounted in a wooden frame and contains at least 30 different gears and has over 2000 inscribed characters.  The device has forced a re-evaluation of the level of technology available in the Classical World as its technical sophistication was not approached again in the Western World until the first mechanical astronomical clocks were built in the 14th century AD.

The current prevalent theory is that the Antikythera Mechanism was a differential gear arrangement designed to calculate planet, sun and moon positions based upon input data.  In essence a mechanical analogue computer.  Below are pictures of a replica of the device:
Next is a video of a working reconstruction of the Mechanism.If you'd like to know more, this article from The Guardian contains videos on the recent scientific investigation as well as a LEGO reconstruction!

The new research on the Mechanism, along with other discoveries in recent decades, illustrate that the Classical World was more technologically advanced, with a more integrated economy and more densely populated than had been previously thought.