Derinkuyu Underground City Turkey In Derinkuyu Turkey there is an underground city with 11 levels. It's able to hold 30-50 THOUSAND people. It has a wine cellar and stables for livestock. Each level has a huge rock circular door that can be shut from the inside to keep people out. It also has an air vent and pluming.They say it was built dug in the 6th or 7th century BC.