In 1902, workers on the island of Malta were digging a cistern for a new housing development when they accidentally cut through the ceiling of this unique structure. Reputed to be the only prehistoric subterranean temple in the world, the Hypogeum (a Latin spelling of a Greek term for “under the ground”) extends downward for three distinct levels, and most of the rooms are covered with an eerie red ochre. Discovered at the deepest level were the scattered bones of nearly 7,000 people, which has led some to posit a long history of human sacrifice. To whom or what they were sacrificed is unknown, but a National Geographic article published in August, 1940 only deepened the mystery, as it reported of a tunnel leading off from the lowest chamber that connected with an underground labyrinth spanning the entire island. Even then, the tunnels had been sealed off after a teacher led some of her students into the labyrinth on a field trip and never returned.