The Antikythera Mechanism is the earliest known device to contain an intricate set of gear wheels. It was retrieved in 1901 from a shipwreck off the Greek island of Antikythera but until now what it was used for has been a mystery.
Although the remains are fragmented in 82 brass pieces, scientists from Britain, Greece and the United States have reconstructed a model of it using high-resolution X-ray tomography. They believe their findings could force a rethink of the technological potential of the ancient Greeks.
I remember reading once a hypothesis that Moore's Law (actually a variant of it - that computer power doubles every 18 months - the original Moore's Law is a manufacturing claim about the number of transistors on a die) held true for the past couple of thousand years. I wish I could find that reference. Anyway, this ancient gdget might support that hypothesis.