Turkey hides an underground city that once sheltered thousands of people

Beneath the town of Derinkuyu, in Turkey’s Cappadocia region, the ground opens into one of the most remarkable feats of subterranean engineering in the ancient world. Carved down through soft volcanic rock, the complex descends roughly 85 metres over multiple levels and was large enough to hold as many as 20,000 people, along with their livestock and food stores. It is the largest excavated underground city in Turkey, and it was designed not for permanent living but for survival during times of danger.

The city is a warren of tunnels, chambers, stairwells and shafts, all hewn from the same friable tufa that makes Cappadocia’s fairy-chimney landscape possible above ground. What sets Derinkuyu apart is how completely its builders thought through the problem of hiding a population for extended stretches without cutting it off from air, water or defense.

Eighty-five metres beneath Cappadocia

According to the documented record of Derinkuyu, the complex reaches a depth of about 85 metres and is organized into descending levels connected by narrow staircases. Its capacity of up to 20,000 inhabitants is what distinguishes it from the dozens of smaller underground refuges scattered across the region. Each floor was self-contained enough to function as its own zone, and the whole structure was carved entirely by hand from the volcanic bedrock, without the reinforcement or shoring a modern excavation of that depth would require.

The stability of the site is itself a subject of study. An engineering analysis presented in Procedia Engineering examined how the pyroclastic rock of Cappadocia allowed such a deep, multi-level city to be excavated and to remain standing for centuries, noting the material’s workability when freshly cut and its hardening on exposure to air.

Rolling stone doors and a deep ventilation shaft

Derinkuyu was built to be sealed. Large circular stone doors, resembling millstones, could be rolled across passageways from the inside, and each level could be closed off separately so that intruders who breached one floor could still be stopped from reaching the next. The doors were designed to be operated only from within, a deliberate defensive choice.

Life underground demanded air and water, and the planners provided both. A ventilation shaft running some 55 metres deep doubled as a well, supplying water to people hiding below and, when needed, to the villagers above. Around this core the city included wine and oil presses, stables, cellars, storage rooms, communal dining halls known as refectories, and chapels. One distinctive space on an upper level features a barrel-vaulted ceiling and is believed to have served as a religious school, with adjoining rooms used as studies.

From Phrygian caves to a Byzantine stronghold

The origins of Derinkuyu reach deep into antiquity. The first caves may have been dug by the Phrygians in the 8th or 7th century BC, cut into the soft rock as the region’s inhabitants learned to exploit the tufa. When Greek gradually replaced the Phrygian language in Roman times, the population expanded the caverns into the deep, multi-level structure seen today, adding chapels and Greek inscriptions. The city reached its fully developed form during the Byzantine era, when it served as a refuge from the Arab raids that made Cappadocia a contested frontier.

Derinkuyu did not stand alone. It was linked to another underground settlement, Kaymaklı, by a tunnel network running some 8 to 9 kilometres — evidence that these complexes formed an interconnected system rather than isolated bolt-holes. Such connections would have allowed people to move between refuges unseen, or to flee from one to another if a single entrance were compromised. The Nevşehir provincial authorities count Derinkuyu among the most significant of the region’s many underground cities, part of a dense honeycomb of dug settlements that riddles the volcanic plateau of central Anatolia.

Centuries of refuge

The function of Derinkuyu remained constant across many rulers: it was a place to disappear when the surface became dangerous. Christian inhabitants used it as protection during the incursions of Timur in the 14th century, and after the region fell to the Ottomans the local population continued to treat the tunnels as hideouts. As late as the early 20th century, Cappadocian Greeks were still retreating underground to escape periodic persecution. A Cambridge linguist working in the area between 1909 and 1911 recorded that when news arrived of massacres elsewhere, much of the population of a nearby town took refuge in the underground chambers and, for several nights, did not dare to sleep above ground.

That long history of use ended abruptly in 1923, when the Christian inhabitants of the region were expelled to Greece in the population exchange between Greece and Turkey, and the tunnels fell silent.

Rediscovered behind a basement wall

For decades the sealed city sat forgotten beneath the modern town. Then, in 1963, a resident renovating his home broke through a wall and found a mysterious room behind it. Further digging revealed the entrance to the vast tunnel network, and the scale of what lay below gradually became clear. The site was opened to visitors in 1969, and roughly half of the underground city is now accessible to the public.

Derinkuyu endures as a reminder that ancient communities, facing repeated threats from above, engineered an entire world below — one with fresh air, running water, storage, worship and defense, all cut patiently from stone. It stands not as a lost mystery but as a carefully documented monument to human ingenuity under pressure.

This article was produced with AI assistance and reviewed by Morning Overview editors.

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