The Hittites are purported to have begun construction of the underground metropolis, but are thought to be responsible for only the first few levels. Following the demise of the Hittite Empire in the 12th century BC, the Phrygians dominated the region until the seventh century BC. It was this civilisation that probably built the majority of the city.

Highly skilled, its craftsmen had the know-how to expertly carve the soft rock, which is fragile and prone to collapse. They hollowed out what's been likened to a human ant farm or rabbit warren with a myriad of tunnels, chambers and halls supported by strategically placed support pillars. No part of the city has ever collapsed, a testament to the brilliance of the Phrygian engineers.

Inside Derinkuyu: the secret underground city of ancient Anatolia