Smaller than Cappadocia’s other subterranean cities like Kaymakli and Derinkuyu, Ozkonak Underground City (Ozkonak Yeralti Sehri) 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, Ozkonak 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. Reaching a depth of 40 meters in total, today only the first four floors of Özkonak Underground City are open. As you wander the tiny corridors, you'll see the sophistication of the city which had a built-communication system made up of pipes that connected all 10 levels. Look out for holes in the walls too — these provided ventilation in the event that Ozkonak city would have to close itself off to the outside world if enemies tried to invade. The underground city also had its own winery and water well, and if enemies did get too close, well Özkonak’s inhabitants were more than ready to pour hot oil on them through secret holes designed for that very purpose.