Smaller than Cappadocia’s other subterranean cities like Kaymakli and Derinkuyu, Ozkonak Underground City (Özkonak Yeraltı Şehri) is also much less crowded. On the northern slopes of Mount Idis, as you hunch to stroll the tiny corridors of this ancient city you'll feel very big compared to the people who once lived here. Likely built in the Byzantine era, though perhaps even older, Özkonak Underground City was rediscovered in the '70s by a local farmer who wondered where his excess crop water was going. Turns out it was going into a huge subterranean city stretching ten floors deep and able to house 60,000 people.