Derinkuyu is one of 36 underground cities built in the Cappadocia region of Turkey. Originally built in the 7th century A.D, Christians hid in the underground tunnels eight floors beneath the surface of the earth as the Arabs rampaged across the land.Derinkuyu is a town and district of Nevşehir Province in the Central Anatolia region of Turkey. According to 2010 census, population of the district is 22,114 of which 10,679 live in the town of Derinkuyu. The district covers an area of 445 km2 (172 sq mi), and the average elevation is 1,300 m (4,265 ft), with the highest point being Mt. Ertaş at 1,988 m (6,522 ft). Located in Cappadocia, Derinkuyu is notable for its large multi-level underground city which is a major tourist attraction. The historical region of Cappadocia, where Derinkuyu is situated, contains several historical underground cities, carved out of a unique geological formation. They are not generally occupied. Over 200 underground cities at least two levels deep have been discovered in the area between Kayseri and Nevşehir, with around 40 of those having at least three levels. The troglodyte cities at Derinkuyu and Kaymaklı are two of the best examples of underground dwellings.