The Antikythera Mechanism

Long suspected as being an astronomical showpiece, navigational instrument or rich man's toy, the Antikythera Mechanism is a bronze mechanism built before the birth of Christ.

New research has convinced scholars in Greece that it is, in fact, the world's oldest analog computer.

Here's the recent news article: Revealed: world's oldest computer

And here is the Wikipediea article on The Antikythera Mechanism