An underground city in Turkey once hid 20,000 people from invaders

In 1963, a homeowner in the Turkish region of Cappadocia knocked down a wall in his basement during renovations and found a passage leading into darkness. Beyond it lay a vast, hidden world: an underground city carved dozens of stories into the soft rock, with room enough to shelter thousands of people, their food and even their livestock. The site, known as Derinkuyu, is the deepest excavated underground city in Turkey.

At its greatest extent the complex could hold an estimated twenty thousand people along with their supplies, sealed away behind massive stone doors that rolled shut from the inside. It was built not as a permanent home but as a refuge, a place to disappear when danger swept across the plateau above.

A city carved downward

Located in the Cappadocia region of central Anatolia, Derinkuyu descends roughly 280 feet, spread across as many as eighteen levels. The upper floors held living quarters and stables for animals, while lower levels contained storage rooms, wine and oil presses, communal kitchens, chapels and even a space interpreted as a school. Everything was hewn from the rock itself, connected by narrow stairways and shafts.

The whole system was designed to be closed off. Great circular stone doors, several feet across and weighing hundreds of pounds, could be rolled across passages to block them, and crucially they were operated from the inside, so defenders could seal themselves in while attackers were left stranded in the tunnels. Each level could be shut independently, so an intruder who breached one floor could still be trapped before reaching the next.

The rock that made it possible

Cappadocia’s underground cities exist because of the region’s unusual geology. Ancient volcanic eruptions blanketed the area in thick layers of ash that hardened into a soft stone called tuff, easy to carve with simple tools yet stable enough to hold its shape once exposed to air. That combination let communities dig extensive complexes without the whole thing collapsing.

The same volcanic landscape produced the region’s famous “fairy chimneys” and cliff dwellings. The broader area, including the rock-cut churches and settlements around Göreme, is protected as a UNESCO World Heritage Site recognized for both its natural formations and its long history of human habitation carved directly into the stone.

Air, water and survival underground

Keeping twenty thousand people alive far below ground required careful engineering. A network of ventilation shafts ran down through the levels, circulating fresh air even to the deepest chambers, so that fires and crowds did not exhaust the supply. Wells provided water, and some were designed so they could not be reached or poisoned from the surface, protecting the hidden population from a siege above.

The presence of stables, presses, storage rooms and chapels shows the city was built for extended stays, not just a quick hiding place. A community could withdraw underground and continue something close to normal life for weeks, tending animals, pressing oil and holding services, while waiting out whatever threat had driven them below.

Who built it, and who hid there

The origins of Derinkuyu are debated. Some researchers suggest the earliest tunnels may date back to the Phrygians around the eighth century BCE, or even earlier to the Hittites, with the complex expanded over many centuries by successive peoples. Whoever began it, later inhabitants greatly enlarged the network.

Its clearest use was as a shelter from invasion and persecution. During the Roman and Byzantine periods, early Christians used the underground cities of Cappadocia to escape raids and religious persecution, retreating below ground when hostile armies passed through. Derinkuyu was even connected by a long tunnel to another underground city nearby, forming part of a wider defensive network.

The engineering choices reveal how seriously the threat was taken. Passages were deliberately kept low and narrow in places, forcing anyone entering to stoop and move in single file, which turned the tunnels themselves into a defense that favored those already inside. Livestock were generally kept on the upper levels, both to limit the waste and smell reaching the living quarters below and to keep the animals near the entrances. Grain stores and protected water sources meant the population could outlast an enemy who had no idea how deep the refuge actually went, and every detail, from the airflow to the layout, was shaped by the need to hold out safely for as long as a siege above might last.

Today the complex is open to visitors, who can descend through its narrow passages past the great stone doors and ventilation shafts. Standing hundreds of feet underground, it is a monument to a simple, stark impulse: when the world above became too dangerous, an entire population could vanish into the earth and wait for it to pass.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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