All labyrinths are puzzling - that's the point of them - but the ancient Hypogeum of Hal Saflieni below the streets of Malta is a particularly perplexing maze. We had no idea it was there at all until it was discovered in 1902, but it appears to have been used six thousand years ago, and for a period of around two thousand years.
The extensive maze features rooms and corridors carved directly from the rock that surrounds them, and also host ancient paintings. Who were these ancient labyrinth enthusiasts?