Derinkuyu

In 1963, a man tore down a wall in his house and noticed an enormous and complex tunnel system behind it. He had rediscovered the ancient underground city Derinkuyu in Turkey. The city had 9 levels, used to house 20,000 people and had amenities such as stables, wineries, schools, and chapels. It was built between 1200 and 800 B.C.