A man knocked down a wall in his basement while renovating his home. Behind it was a staircase leading down into an entire hidden city.
In 1963, that discovery in the town of Derinkuyu, in Turkey's Cappadocia region, revealed one of the largest underground cities ever found — a multi-level complex carved roughly 85 meters (280 feet) into soft volcanic rock, large enough to have sheltered as many as 20,000 people along with their livestock and food stores.
Who Actually Built It
Locally, Derinkuyu has long been nicknamed the “City of Giants” — a reflection of how implausible its scale and precision seemed to the people who found it, not a literal archaeological claim. The documented history is far more grounded, and arguably more impressive for being entirely human.
Archaeologists generally credit the earliest excavation to the Phrygians, a skilled Iron Age people known for their rock-cut architecture, working in the region around the 8th to 7th century BC. Some researchers believe even earlier work may date back to the Hittites, centuries before that. The city reached its full, multi-level form much later, during the Byzantine era, when Greek-speaking Christian communities expanded the original chambers into the deep, complex network visitors see today — adding chapels, a religious school, and Greek inscriptions still found on its walls.
Built for Shelter, Not Mystery
Derinkuyu's purpose is well understood: defense and refuge. Its location made it a natural place to hide from invading forces over many centuries. Byzantine Christians used it to shelter from Arab raids between the 7th and 11th centuries. Centuries later, the same tunnels sheltered people from Mongol incursions under Timur in the 14th century, and later still, from persecution under the Ottoman Empire. Cappadocian Greek and Armenian communities were still using the tunnels for safety as recently as the early 20th century, before the city was finally abandoned following the 1923 population exchange between Greece and Turkey.
What's Inside
The city was built with genuine ingenuity. Massive circular stone doors, some weighing hundreds of kilograms, could be rolled into place from the inside to seal off individual levels — heavy enough to block invaders, but engineered to be moved easily by a single person from within. A ventilation system of more than a dozen large shafts, some over 55 meters long, kept air circulating throughout the complex even at its deepest levels. Excavated spaces include stables, wine and oil presses, storage rooms, communal kitchens, and chapels, along with what's believed to have been a religious school on the second level.
The ancient Greek writer Xenophon, a student of Aristotle, described people in the region living in underground dwellings accessed by narrow, well-like passages in his 4th-century BC work “Anabasis” — a detail many historians connect to Cappadocia's underground cities, including Derinkuyu, even though he doesn't name it directly.
An Unfinished Picture
Despite decades of study, only about half of Derinkuyu has been excavated and opened to the public since 1969. Derinkuyu also connects to at least one other underground city nearby, Kaymaklı, via a tunnel roughly 8 kilometers long — and further research continues into the broader network beneath the region. Notably, no cemetery or human remains have been found within the excavated portions of the city, something that remains genuinely unexplained.
Frequently Asked Questions
Was Derinkuyu really built by giants?
No. “City of Giants” is a local nickname reflecting the scale of the engineering, not an archaeological finding. The documented builders were the Phrygians, later expanded by Byzantine-era Christian communities.
How deep does Derinkuyu go?
Approximately 85 meters (280 feet), spanning multiple underground levels.
How many people could it hold?
Estimates suggest it could shelter as many as 20,000 people, along with their livestock and food supplies.
Why was Derinkuyu abandoned?
Its last inhabitants, Cappadocian Greek Christians, left in 1923 as part of a population exchange between Greece and Turkey. The tunnels sat largely forgotten until their rediscovery in 1963.