Ozkonak town of Nevsehir city which 14 km northeast of Avanos is located on the northern slopes of the Idis Mountain, there are supernormal underground structure of Ozkonak underground city. There is only a single main passage, and the whole city is built along it by cut volcanic granite. Ozkonak underground city has long, narrow connections, about 5cm in diameter, connect the different levels and naighbouring chambers. They were used for communication between the levels and for ventilation. There are ten rooms, four big salloon, eight water well, four tombs, ventilation system, winery and closeable doors via circle stone like millstone for security reason. Additionally there are so many ambushes in the long narrow tunnels for to mislead enemy in the Ozkonak underground city.
Common among the underground cities are huge millstone doors. The millstones were rolled into narrow sections of the passage and wedged from behind. Here at Ozkonak, they have a special feature in front of the millstone doors on the ceiling are small holes. They are connected with a tunnel above, and were used to pour hot oil on the enemy or to spear them.
Ozkonak underground city was discovered in 1972, there are ten floors totally but only four floors open now because of has not been completely cleaned yet.