Derinkuyu, Cappadocia, Turkey

Our first example is probably one of the most well-known ancient underground cities discovered! The lunar-like region of Turkey’s Cappadocia contains no less than 36 underground cities, but Derinkuyu is likely the deepest and most impressive of them all.

The expansive network of passages and tunnels goes back to the 8th century BC and is considered a shelter to protect people in times of war.

Due to this, the once-secret ancient underground city is a self-sufficient metropolis inhabiting ventilation shafts, kitchens, wells, schoolrooms, oil presses, a bathhouse, a winery, and living space for over 20,000 people on 18 stories.

The most unique feature of Derinkuyu is the cruciform church. But, the massive city remained hidden from the world until 1963.