Kappadokien's underground cities, built thousands of years ago for defense and everyday living, are among the most impressive engineering marvels in history. Derinkuyu, with its corridors descending up to eight levels and its advanced ventilation systems, once sheltered tens of thousands of people. Kaymaklı, on the other hand, stands out for its wider horizontal tunnels and shared production areas. In this article we share the floor plans of both cities, their historical background, points to pay attention to during a visit, and practical tips for avoiding claustrophobia.