A complex ventilation system was discovered ... None of them, however, matches the size and intricacy of Derinkuyu. The underground tunnels did not only house humans - livestock were also kept ...

Originally known at Elengubu, the ancient city of Derinkuyu stretches ... there is also a complex ventilation system that allowed dwellers to stay in the underground city for months on end ...

Ancient underground cities are fascinating. Many people called them home, which shows the resilience of societies through time.