An ancient complex system of tunnels found in turkey is called Derinkuyu Underground City. It has 11 floors extending to the depth of 85 meters. This city is so huge that it could house as much as 30 000 people and its livestock, food stores, and it even had temple rooms, stables, storehouses. All of this suggests that this tunnels were a permanent residing place of the residents. City also featured ventilation shafts and smaller air shafts which provided air to the lowest levels of the city.