The underground cities of the Byzantine Empire - Veronica Kalas

The breathtaking geological formations of Cappadocia present one of the most astonishing landscapes on Earth. Also known as fairy chimneys, these sturdy stone cones were created by massive volcanic eruptions, which poured countless tons of ash across what would eventually become part of central Türkiye. Over millions of years, that volcanic fallout hardened into a porous rock known as ignimbrite, which was sculpted by centuries of wind and rain into the colorful spires we see today.

But this impressive terrain hides an equally remarkable feat of pre-modern engineering: a network of extensive underground cities stretching deep below the surface. Archaeological work on these mysterious ruins only started in the 1960s, so researchers still have many unanswered questions. But they have been able to determine some of the basics. Cappadocia’s underground settlements date back to the Middle Ages when the region was part of the eastern territories of the Byzantine Empire.

Throughout the 7th and 8th centuries, this border region was frequently under siege from Arab invaders, which may have led locals to seek refuge underground. Initially, archaeologists assumed these subterranean cities and sanctuaries were created by Greek-speaking Orthodox Christian monks due to the numerous Byzantine churches and copious religious imagery. But further investigation revealed intricately designed layouts and elements of domestic architecture that could only have been produced by master masons.

Typically, these craftsmen would have built such structures with brick and stone, but under the surface they carved their designs directly into the rock. All these complexes were connected by stairs and tunnels which could be sealed off with large boulders for protection. Residents dug deep enough to reach the water table, ensuring their access to water during lengthy sieges. And vertical ventilation shafts connect these cities to the sky, circulating cool, fresh air to the residences inside.

In addition to living spaces, these dwellings had wine presses, cooking areas, and stables for livestock. Some chambers even offered old-fashioned lavatories, where waste could be washed into deep pits or covered with lime. Normally, this approach would still have left some stench, but the region’s absorbent volcanic rock helped maintain a dry and odor-free environment. The rock’s composition also helped ensure stable temperatures throughout the year, making these spaces ideal for long-term living and food storage.

By the 11th century, the Byzantine Empire secured its eastern frontier, bringing peace and stability back to the region. But rather than abandoning their underground settlements, locals expanded them into the landscapes above. Building directly into the region’s rocky cliffsides, stoneworkers skillfully carved dwellings with open courtyards and adorned their entrances with elegant facades. Numerous churches were also carved from the rock, all designed in the standard architectural styles of the Byzantine Empire during the 9th to the 11th centuries.

This included simple structures with altars and apses as well as intricate designs featuring columns and domes. And on the inside, many showcased vibrant wall paintings depicting detailed Christian iconography. These paintings are still visible today, making Cappadocia one of the most significant repositories of Byzantine art in the world.

But while these paintings and stony structures endured, their inhabitants were forced to move on. It’s believed that the Byzantines started vacating the region when the Seljuk and Ottoman Turks took hold of it in the late 11th century. Over the following centuries, local farmers and villagers used these spaces for storage and squatting, and there's evidence of some inhabitants as recent as the early 20th century.

However, in the past few decades, these cities have been recognized as international heritage sites requiring care and preservation. This designation has earned them government protection and attracted both curious researchers and tourists eager to explore their labyrinthine passageways. Derinkuyu, which stretches up to 85 meters below the ground, and Kaymakli are the two best known and most visited. But Göreme, Ihlara, and many other valleys are where you can see the finest preserved churches, all with spectacular Byzantine architecture and wall paintings.

And as researchers continue to excavate these sites, they'll undoubtedly uncover even more secrets from this buried history.