Secret Underground Cities Around the World

Some underground cities were built for comfort, but a lot of them were built for survival, and the timeline is downright wild. Long before nuclear bunkers were a thing, people were already carving rooms into the earth to hide, store food, and keep going when the world above ground turned hostile.

Picture rolling stone doors sealing levels like a giant puzzle box, early Christians slipping into tunnels to dodge Roman and later Arab forces, and soldiers in WWI scratching their names into quarry walls. Then zoom out to the broader mess: defense from raids, religion tied to burial and sanctuary, climate control, and even whole industries like salt mines and water storage.

And once you start, it gets hard to stop, because the most famous “secret” networks were never really meant to stay secret.

Why Civilizations Built Underground Cities

The reasons are short and old:

• Defense: invasions, raids, religious persecution
• Climate: extreme heat or cold above ground
• Religion: burial, ritual, sanctuary
• War: Cold War nuclear shelters, WWII bombings
• Industry: salt mines, quarries, water storage

The earliest known underground cities date back thousands of years. The newest were built in the 1970s under Beijing in case of nuclear attack. Most fall somewhere in between.

The Most Famous Secret Underground Cities

Take a look:

Derinkuyu, Turkey

The undisputed king of underground cities. Up to 60 meters deep, with rolling stone doors that could seal each level from the others. Early Christians used it to hide from Roman and later Arab forces.

The deeper Derinkuyu underground city was connected by a 9-kilometer tunnel to another full underground city at Kaymakli. The full network has still not been completely mapped.

commons.wikimedia.org

Kaymakli, Turkey

Wider but shallower than Derinkuyu, with eight levels, only four open to visitors. Storerooms outnumber living spaces. Some researchers think Kaymakli was where food was kept and Derinkuyu was where people sheltered.

commons.wikimedia.org

Naours, France

In Picardy, a quarry first cut in the third century became a sanctuary during the Thirty Years War. The complex has more than 300 chambers, chapels, wells, and stables. It could hold about 3,000 people. During WWI, allied soldiers used it as a base and carved their names into the walls. Many of those signatures are still legible.

commons.wikimedia.org

Wieliczka Salt Mine, Poland

Not strictly a city, but functionally one. Mining began in the 13th century and continued until 2007. The complex stretches 287 kilometers across nine levels.

Miners carved chapels, statues, and even a full cathedral entirely out of salt, including chandeliers. The Chapel of Saint Kinga is still used for services. UNESCO listed it as a World Heritage site in 1978.

commons.wikimedia.org

Orvieto, Italy

The Italian hill town sits on a plateau of soft volcanic tuff. Etruscans started digging into it in the 6th century BCE. Twenty-five centuries of expansion left more than 1,200 tunnels and chambers beneath the modern city, including wells, cisterns, dovecotes, oil presses, and WWII bomb shelters.

commons.wikimedia.org

And if you think underground is extreme, ancient cities that sank beneath the sea and stayed inhabited for centuries are even wilder.

Beijing Underground City (Dixia Cheng)

In the 1960s and 70s, Mao Zedong ordered a massive bunker network built under Beijing in case of nuclear war with the Soviet Union. The complex was reportedly designed to shelter up to 40% of the city's population, with schools, hospitals, mushroom farms, and 90 entrances hidden across the city.

The Soviets never attacked. The Beijing Underground City was eventually partially opened to tourists in 2000 and then closed again for renovations.

commons.wikimedia.org

Coober Pedy, Australia

Built above ground first, then pushed below it. Temperatures in the South Australian outback regularly hit 45°C in summer. Residents started digging homes into the hillsides during the opal-mining boom of the 1910s, and they never moved back to the surface.

Today around 1,600 people live in Coober Pedy, with most homes, hotels, churches, and shops carved into the rock. It is one of the few inhabited underground cities still in everyday use.

commons.wikimedia.org

Setenil de las Bodegas, Spain

Not a city below ground but a town built into the underside of a massive rock overhang. Roman-era occupation, possibly earlier. The cliff acts as a giant roof, keeping homes cool in summer and warm in winter. Setenil is the closest living example of how naturally protected sites became permanent settlements.

commons.wikimedia.org

Matmata, Tunisia

Berber troglodyte dwellings carved into the soft yellow earth. The pit-style houses date back centuries and have been continuously occupied. Most visitors recognize Matmata as the filming location for Luke Skywalker's home on Tatooine in the original Star Wars.

commons.wikimedia.org

Burlington Bunker, England

A 35-acre underground complex built 30 meters below the village of Corsham in Wiltshire. The British government planned to use it as a relocation site in the event of nuclear war. It included its own railway platform, hospital, BBC studio, and accommodation for 4,000 staff. The site was declassified in 2004.

commons.wikimedia.org

That’s why Derinkuyu, with its up-to-60-meter depth and stone doors that could seal entire levels, feels less like a legend and more like an escape plan with good architecture.

Meanwhile Kaymakli’s eight levels, with storerooms outnumbering living spaces, makes you wonder who was planning for “shelter” versus who was planning for “ration day.”

And if you think that’s intense, Wieliczka in Poland keeps escalating, stretching across nine levels for centuries until miners carved chapels and a cathedral out of salt.

The Lost Underground Cities

Some underground cities are still being discovered. Excavations near the Hagia Sophia in Istanbul, beneath the Giza pyramids, and across central Anatolia regularly uncover sealed tunnel networks. In 2014, archaeologists in the city of Nevsehir, Turkey, announced a possible underground city even larger than Derinkuyu. Surveys are ongoing.

Other ancient subterranean sites have been documented but never fully explored. The Catacombs of Paris hold the bones of more than six million people and stretch across hundreds of kilometers. Most of them are off limits to the public. So-called cataphiles still sneak in and map them by hand. The relationship between these burial galleries and other crypt sites like the Sedlec Ossuary is one of the strangest threads in European sacred architecture.

How They Stayed Hidden

A secret underground city does not survive for centuries by accident. Most of them rely on the same combination:

• Local knowledge that gets lost or suppressed
• A narrow, disguised entrance
• Soft rock that can be sealed quickly
• A population that needs them, until it doesn't

Once the original reason for hiding disappeared, most communities sealed the entrances and moved on. The cities themselves stayed intact, frozen, waiting for someone to knock down the wrong wall.

The pattern repeats above ground too. The underwater cities lost to rising seas, the abandoned coastal settlements, the ghost towns of the American West. Civilizations leave behind whatever they couldn't carry. The ones that survive best are usually the ones built into rock.

For the American side of this story, the underground cities in the US cover a different history, older mining tunnels, Prohibition-era speakeasies, and Cold War bunkers, most of them still preserved.

The earth was basically the original doomsday app, and it kept getting new updates.

Want proof of how deep it went, read about the 1963 sledgehammer discovery of Derinkuyu.