The Antikythera Mechanism
1st Century BC, Classical Greece. Discovered in 1974. Could predict the position of the five known planets as well as solar eclipses.
Consider how this type of knowledge is related to Greek philosophy's faith in mathematical reason.
Seven minute video (skip to 4:15 for mechanism summary
Digital reconstruction (3:30 long)
NOVA: Ancient Computer (52:00 long)
Also see:
Erastosthenes