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

Beneath the wind-carved rock towers of Cappadocia in central Turkey lies a warren of tunnels and chambers that once served as one of the largest refuges ever carved by hand. The complex near the modern town of Derinkuyu, in Nevşehir Province, drops roughly 85 meters below the surface across as many as 18 levels, and archaeological estimates put its capacity at around 20,000 people along with their livestock and stored grain.

That scale makes it the largest excavated underground settlement in Turkey and the best known of dozens of similar complexes scattered across the region. Its story spans nearly three thousand years, several empires, and one accidental discovery involving a homeowner’s sledgehammer.

Carved Out of Cappadocia’s Softest Rock

The region’s landscape is dominated by tuff, a rock formed from compacted volcanic ash that erosion has sculpted into the area’s famous “fairy chimney” spires. The same softness that lets wind and rain shape the surface made it possible for people to dig by hand below it. Cappadocia holds hundreds of underground dwellings, storage chambers and refuges, with roughly 40 running at least two levels deep. None approaches the scale of Derinkuyu, and despite the softness of the stone, engineers who study the site note that none of its floors has ever collapsed, a result credited to deliberately placed support pillars throughout the tunnel network, according to Wikipedia’s summary of the site’s geomechanical surveys.

A City Built in Stages, Possibly Starting With the Phrygians

Exactly who first broke ground remains debated. Some archaeologists trace the oldest tunnels to the Phrygians in the 8th or 7th century BC, while other researchers have floated the Hittites around 2000 BC or early Christian communities in the first centuries AD. What is better documented is the complex’s expansion under Byzantine rule, when local Christians deepened and extended the tunnels, adding chapels and Greek inscriptions. The final major phase of construction, bearing a distinctly Christian character, dates to roughly the 6th through 10th centuries AD, as the population dug in against Arab raids that struck the Byzantine frontier for four centuries.

Stone Doors That Locked From the Inside

Defense shaped nearly every design choice. Massive circular stones could be rolled across doorways to seal the city from within, and each level could be closed off independently, allowing residents to isolate a breached section, move fighters between floors, or mount a counterattack without exposing the rest of the population. Between the living quarters, builders carved stables, wine and oil presses, cellars and communal kitchens fitted with tandoor-style ovens still used in Cappadocian villages today. A barrel-vaulted hall on the second level, unique to Derinkuyu among the region’s underground cities, is thought to have functioned as a religious school, with adjoining rooms serving as study chambers.

An Engineered Air and Water System

Sealing tens of thousands of people underground created an obvious problem: breathable air. The builders answered it with more than 15,000 narrow ventilation shafts, most only about 10 centimeters wide, threading air down as far as the eighth level. A wider central shaft, roughly 55 meters deep, doubled as a well, drawing water for both the town above and anyone sheltering below when the surface was too dangerous to reach. Generations of Turkish villagers drew from these same shafts for household water without realizing what lay beneath their buckets — the town’s name, Derinkuyu, translates simply to “deep well,” according to the Atlas Obscura account of the site’s rediscovery, drawn from reporting on Cappadocia’s underground settlements.

Living Quarters High, Storage and a Dungeon Below

The layout followed a rough logic tied to that airflow. Upper floors, which received the most ventilation, served as living and sleeping quarters, while lower levels were set aside mainly for storage of food and supplies and, on at least one floor, a dungeon. Between those extremes sat rooms built for nearly every daily need: a wine press, pens for domestic animals, a small convent, and several chapels, the most elaborate of which was a cruciform church carved into the seventh level. Some researchers also point to a more mundane advantage of life underground — Cappadocia’s surface swings between bitterly cold winters and scorching summers, while the tunnels hold a roughly constant, moderate temperature year-round, which would have made the complex useful for storing harvests away from both extreme weather and thieves even in peaceful periods.

From Refuge of Last Resort to Rediscovery

Derinkuyu likely reached its peak population during the Arab-Byzantine wars between roughly 780 and 1180, when Christian villagers retreated underground to escape Umayyad and later Abbasid raiding parties. The underground cities of the region saw renewed use during Seljuk incursions in the 11th century and Mongol raids under Timur in the 14th, and Cappadocian Greek and Armenian communities continued sheltering there into the 20th century during periods of persecution. An 8- to 9-kilometer tunnel network links Derinkuyu to the nearby Kaymakli underground city. Use of the complex ended in 1923, when Cappadocia’s Christian population was relocated to Greece under a formal population exchange between the two countries, and knowledge of the tunnels faded until 1963, when a Derinkuyu resident renovating a basement broke through a wall into a hidden chamber. Excavation since then has turned up more than 600 separate tunnel entrances across the town, many concealed beneath private homes. The site is now part of the UNESCO-listed Göreme National Park and the Rock Sites of Cappadocia, with roughly a third of its levels open to visitors.

This article was produced with the assistance of AI and reviewed by an editor.

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