http://spi0n.fr/blog/photos-images-insolites/la-ville-souterraine-mysterieuse/
Quick translation:
Discover in 1963
Go under 85 meters (915 foots)
Can receive 10.000 inhabitants
Used as refuge by first Christians and frequent invasions
http://en.wikipedia.org/wiki/Derinkuyu_Underground_City
Quick translation:
Discover in 1963
Go under 85 meters (915 foots)
Can receive 10.000 inhabitants
Used as refuge by first Christians and frequent invasions
http://en.wikipedia.org/wiki/Derinkuyu_Underground_City