The Antikythera calculator dates from 150 BC. It is a classic oopart. It was made by Greeks, perhaps Archimedes or Aristarchos. It calculates the location of solar and stellar objects in the sky given a date that is entered mechanically. It is the size of a smaller college textbook.

http://en.wikipedia.org/wiki/Antikythera_mechanism

http://en.wikipedia.org/wiki/Out-of-place_artifact