In this Nature Video production, the ancient Greek astronomical calendar known as the Antikythera mechanism, considered by some to be the first computer, is explained in Lego form. (via Boing Boing)
If you're still reeling from the news that the Antikythera mechanism actually does have a relatively mundane purpose, there are plenty of other inexplicable historical objects for you to latch on to. The celestial globes of medieval Islam, however, should no longer be on your list.
These hollow spheres of brass were used as maps of the positions of the stars and planets, and so used to solve ancient astronomy problems. Many of the more than one hundred spheres in museums today were cast in two pieces, and then fitted together, leaving a seam. The rest seem to have been cast in one piece, seamlessly. Emilie Savage-Smith tackled the question of how ancients could have crafted seamless spheres, and found an answer.