These must have been constructed for security purposes against the danger presented by mainly Arab raiders. The openings were closed by huge mill stones. To the underground city called Derinkuyu (deep well) flight of stairs which starts from third or fourth storeys takes the visitor to the sanctuaries. The cities at Kaymakli, Ozkonak, Mucur, Orentepe, Gumuskent,Tatlarin, Ovaoren, Gokcetoprak are like modem apartment houses.
The dryness and the property of not absorbing humidity of the tuff made life easy. Even today these underground chambers are used to store lemons, oranges and straw. The underground cities such as Derinkuyu, and Ozkonak have been fitted out and the inside is illuminated and made ready to receive visitors. There must be other such underground cities awaiting their discovery.
The underground city Derinkuyu is in the centre of the actual city and consists of seven levels or storeys which descend to 85 meters beneath the earth’s surface. All the storeys have access to the deep well at the bottom. There are two of which the apertures have been hidden lest they be poisoned by the enemy during a raid. At the bottom is a church in the shape of a cross and the chorus is beside the well.
The underground city next in importance is at Kaymakli at a distance of 9 km. This one also is at the centre of the town, right beneath the Kaymakli Castle. The fact that there are cellars, silos and dwelling chambers indicates that people could take refuge here and live in here for over long periods of time.