The Derinkuyu underground city is an ancient multi-level underground city in the Derinkuyu district in Nevşehir Province, Turkey, extending to a depth of approximately 85 metres. It is large enough to have sheltered as many as 20,000 people together with their livestock and food stores.
The underground city at Derinkuyu could be closed from the inside with large stone doors. Each floor could be closed off separately. The city could accommodate up to 20,000 people and had amenities found in other underground complexes across Cappadocia, such as wine and oil presses, stables, cellars, storage rooms, refectories, and chapels. Unique to the Derinkuyu complex and located on the second floor is a spacious room with a barrel-vaulted ceiling. It has been reported that this room was used as a religious school and the rooms to the left were studies.
Starting between the third and fourth levels are a series of vertical staircases, which lead to a cruciform church on the lowest (fifth) level. The large 55-metre ventilation shaft appears to have been used as a well. The shaft provided water to both the villagers above and, if the outside world was not accessible, to those in hiding.