An 18-story underground city in Turkey could once hide 20,000 people

Beneath the rolling volcanic landscape of the Cappadocia region in central Turkey lies an entire city carved downward into the earth. Known as Derinkuyu, the subterranean complex descends through many levels and, at its fullest, is estimated to have been capable of sheltering many thousands of people along with their livestock and provisions.

The scale of the excavation is staggering. Generations of inhabitants dug through soft rock to create a self-contained refuge, complete with living quarters, storerooms, wells and ventilation, all hidden safely below the surface of the ground.

A city carved straight down

Derinkuyu was hewn into the region’s distinctive volcanic tuff, a soft stone that can be cut with hand tools yet hardens on exposure to air, making it ideal for carving stable underground spaces. Rather than building upward, its makers excavated downward, producing a warren of chambers and passages stacked over numerous levels.

The complex is often described as reaching around 18 levels and extending tens of meters beneath the surface, though not all of it is accessible today. The wider cultural landscape of Cappadocia, including its rock-cut settlements, is recognized by UNESCO as a site of outstanding value.

The geology of Cappadocia made the whole enterprise possible. Ancient volcanic eruptions blanketed the region in thick layers of ash that hardened into workable stone, and over time wind and water sculpted the surface into a landscape of cones and valleys. Beneath that surface, the same soft rock invited people to dig, offering shelter that was cool, stable and easy to expand.

Room for thousands underground

At its peak the city is thought to have been able to accommodate a large population, with estimates commonly cited in the range of many thousands of people. Alongside the residents, the complex could hold livestock and enough stored food and water to sustain everyone for extended periods.

To function as a refuge for so many, Derinkuyu was far more than a set of hiding holes. It included stables, cellars, kitchens, wine and oil presses, wells, and even spaces interpreted as chapels and communal areas, effectively reproducing the essential functions of a surface town below ground.

The range of functions built into the city is striking. Beyond simple shelter, its inhabitants could press oil and wine, stable their animals, worship and store harvests, all without emerging. That completeness meant a community could carry on something close to normal life underground, not merely survive a brief scare before returning to the surface.

Engineering for survival

Keeping thousands of people alive underground required solving serious practical problems, above all the supply of fresh air. The city was fitted with a network of ventilation shafts that drew air down through its many levels, allowing people and animals to breathe even in the deepest chambers.

Access to water came from wells that could be reached from within, so inhabitants did not need to surface to drink, and the wells were arranged to avoid contamination from outside. These systems reflect careful planning aimed at letting the population endure long stretches sealed off from the world above.

Temperature was another quiet advantage of building downward. Deep below the surface, the rock kept the chambers cool in summer and comparatively mild in winter, easing the strain of sheltering many people and animals for long stretches. Combined with the steady air drawn through the ventilation shafts and the protected wells, this natural climate control helped make prolonged underground living not merely possible but bearable.

Sealed against invaders

Security was built into the design. At key points along the passages, large circular stone doors could be rolled into place to block corridors from the inside, sealing off sections against anyone trying to force their way in.

These heavy stone discs could be moved only from within, giving defenders control over the entrances while denying it to attackers. The layout of narrow, twisting passages further favored those who knew the city and hindered intruders, turning the entire complex into a formidable stronghold.

The defensive features reflect a world in which sudden danger was a recurring fact of life. Communities that could vanish below ground, seal the passages behind them and wait in safety held a decisive advantage over raiders who found only empty houses above. The city’s design turned concealment itself into a form of protection.

A refuge across the centuries

Scholars believe underground cities like Derinkuyu were used over long spans of history as places of refuge, allowing communities to disappear below ground during times of raiding, warfare or persecution and wait out the danger in safety. The ability to hide an entire population, with food and animals, was a powerful form of protection.

Derinkuyu is connected by tunnels to other underground settlements in the region, hinting at a broader network of subterranean refuges across Cappadocia. It endures as a striking monument to human ingenuity under threat, as reflected in reference accounts such as those maintained by Britannica.

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

More from Morning Overview