The Antikythera mechanism was a primitive computer, created in Greece over two thousand years ago to predict the positions of planets. Researchers at UCL made this fascinating video that covers some recent discoveries they made about the machine:

Besides the fact that Greek astronomers managed to make such a remarkable device thousands of years ago, I also wonder why ancient societies were so interested in the motions of the planets. It seems to be a feature of every civilization I have learned about. What drew people across the world to study the night sky, and to notice and track the motion of the tiny points of light that dotted it?