Why is it so important?
The Mechanism provides a unique window on history, allowing us to view the collected astronomical knowledge of the Ancient Greeks, and through them the knowledge of the Ancient Babylonians. In many ways the Mechanism provides us with an encyclopedia of the astronomical knowledge of the time.
In addition, it also stands witness to the extraordinary mathematical and engineering capabilities of the Ancient Greeks. The Mechanism is thought to date from between 150 and 100 BC and it precedes any other known clockwork mechanisms of similar complexity by more than a millennium. The level of engineering in the mechanism is astonishing by any standards.