Man discovers ancient underground city in his own basement.

A man in Turkey rediscovered the ancient underground city of Derinkuyu in the 1960s when he knocked down a wall in his basement and found a tunnel. The subterranean city, which once housed 20,000 people, stretches 280 feet below the Earth's surface in the Cappadocia region of Turkey. Now part of a UNESCO World Heritage site, Derinkuyu is open to visitors, although they can only explore eight of its 18 levels.