The Antikythera Mechanism is considered the oldest computer in the world. In fact it seems it is actually even older than originally believed. Researchers at the National University of Quilmes, in Argentina, have studied the device again and now determine that it could date back as far 205 B.C. which is approximately 100 years earlier than they thought before.
The Antikythera Mechan ism was actually discovered within a sunken shipwreck at the bottom of the Aegean Sea (near the island of Antikythera, hence its name).