Absolutely INCREDIBLE DISCOVERY
 کشفی بی نظیر: شهر زیرزمینی "درین کویو" در ترکیه

In 1963 Inhabitants of Derinkuyu (in the region of Capadocia,Central Antolia ,Turkey) by chance discovered the underground city of Derinkuyu:1400a.c 

https://www.youtube.com/watch?v=dxW26pAIG9M