Derinkuyu Underground City is an ancient multi-level underground city in the Derinkuyu district in Nevşehir Province, Turkey. With its eleven floors extending to a depth of approximately 85 m, it was large enough to shelter thousands of people together with their livestock and food stores. It is the largest excavated underground city in Turkey and is part of a network of several underground complexes found across Cappadocia.
The first inhabitants of Cappadocia area have opened deep cavities within the volcanic rocks due to escape from the attacks of the wild animals and hard winter conditions and then they have enlarged these cavities according to their daily needs, they opened new cavities and created the underground cities connecting these cavities with tunnel and labyrinths.In all of the underground cities there are ventilation chimneys reaching place by place to a depth of 80 and until the underground waters. These chimneys were opened due to meet the need of both the ventilation and water. Within the cities that are tepid in winters and cool in summers there are kitchens, cribs, wine houses, depots for cereals, meeting saloons, toilets shortly every kind of living space necessary for living. Within all the cities there are locking stones which can be opened and closed only from inside against to the threats which may come from outside.The oldest written source about underground cities is the Anabasis named book of Xenophon (Written around B.C. 4). In the book is mentioned that the people living in Anatolia have caved their houses underground and that the houses are connected to each other with holes: "The houses were built underground; the entrances were like wells but they broadened out lower down. There were tunnels dug in the ground for the animals wkile the men went down by ladder. Inside the houses there were goats, sheep, cows and poultry with their young..."