Dry and fruitless heights central Cappadocia (modern Turkey) have served as an ideal refuge for the early Christians, seeking safety in flight from religious prosecutions and invasions of Arabs. In soft volcanic rocks they have cut more than . They represented covered from the extraneous eye, well organised, safe and independent inhabited complexes which could place to 30 000 persons.
The city of Derinkuju (in drawing the ancient plan of a vault and modern photos), consisting of eight levels where stables, school, a table hall, churches took places, table, inhabited quarters, wine cellars, a reservoir, warehouse and prison is more thoroughly investigated. Here ventilating apertures of that time till now function, therefore, light at the expense of fire allows to carry out photographing without flash.
In case of danger inhabitants filled up with huge stones passes and corridors. Between city levels in a floor small apertures for interaction between the next floors have been cut.
Eight floors of a city are accessible to tourist excursions, and lowermost of them is on depth of 54 m. However, scientists consider, that while 15% of all area of a city which had more many levels located more low under the earth are revealed only.