Cappadocia – the incredible geological spectacle with its fairy chimneys and eroded caverns is also the home to over 200 underground cities. Derinkuyu is 18 stories and 60 meters deep – making it one of the deepest underground cities in the world. At its deepest point the extraordinary engineers of the past have ensured that there was fresh flowing water and fresh air via a network of about 1500 ventilation ducts connected to a 55m deep ventilation shaft. This city is believed to be able to house 20 000 people complete with stables, cellars, storage rooms, refectories, and chapels.