Approximately 60m deep, the ancient multi-leveled underground city of Derinkuyu is the largest of its kind in Turkey. Located in Cappadocia, it is five storeys deep and could house up to 3000 people, plus livestock and storage space. It is believed that both the Phrygians and Hittites built the underground cities during the 1st millennium BC, however historians have differing views. The unique security systems implemented indicate people who were trying to hide, or protect themselves from enemies constructed the cities.
