Scientists recently announced that they discovered how the Antikythera Mechanism was supposed to work. The 2000-year old analogue computer was discovered in the early 1900s but its functioning was always surrounded by uncertainties.
The study was coordinated by Mike Edmunds and Tony Freeth from the Cardiff University. Thanks to X-Rays and tri-dimensional scanning the researchers were able to read the inscriptions inside the mechanism and to interpret its functioning.
Apparently the ancient computer was used measure the movement of different astronomical cycles. There was two displays, the first one would display the passages of the Sun and the Moon through the different constellations of the Zodiac. The second display, instead, would display the time in relation to astronomical cycles through pointers.