Derinkuyu Underground City — After Hours with a Geologist Guide

Derinkuyu is an underground city carved 85 metres into the earth, with ventilation shafts, wells, churches, wine presses and stables for 20,000 people. It was occupied continuously from the Hittite period through to the 1920s. Tour groups are in and out in 45 minutes. I arrange after-hours access for small groups and we spend two hours going to the deepest levels that day-tours skip, and I explain the geological process that made this possible — because without understanding the ignimbrite rock, the construction makes no sense.