In 1963, a man renovating his home in Turkey noticed his chickens kept disappearing into a crack in his basement wall, when he dug it open, he found the ancient city of Derinkuyu, an 18-level city 85m underground that could shelter 20,000 people

In 1963, a resident in Derinkuyu, in Turkey’s Cappadocia region, reportedly became curious after his chickens repeatedly disappeared through a narrow opening in the basement of his house. During a house renovation, the resident widened the crack for inspection and stumbled upon a hidden passageway that led to a huge underground settlement.

Raccontata datimesofindia.indiatimes.com