Hagia Sophia is more than just an architectural masterpiece—it is a living testament to history, faith, and mystery. Built in 537 AD by the Byzantine Emperor Justinian I, it has served as a cathedral, a mosque, a museum, and now, once again, a mosque. Over the centuries, it has witnessed the rise and fall of empires, from the Byzantines to the Ottomans, and today, it welcomes over 4 million visitors annually.
However, beyond its majestic dome and intricate mosaics lies something even more mysterious—a hidden world beneath its foundations. For centuries, rumors have circulated about underground tunnels, secret chambers, and lost treasures beneath Hagia Sophia. Some claim these tunnels were ancient escape routes, while others believe they connect to hidden catacombs, forgotten by time.
But are these just myths, or is there truth beneath the surface?
The Legends of Hagia Sophia’s Underground Tunnels
For generations, stories have persisted about a vast underground labyrinth beneath Hagia Sophia. Some of the most popular theories include:
- Escape Tunnels – Secret passages used by Byzantine emperors and clergy to flee during attacks.
- Buried Treasures – Hidden wealth, relics, or sacred objects stashed away before the Ottoman conquest in 1453.
- Subterranean Connections – Tunnels linking Hagia Sophia to the Hippodrome, Basilica Cistern, and even Topkapı Palace.
These theories have fascinated historians, explorers, and researchers for decades. But what actual evidence do we have?
The First Exploration – Göksel Gülensoy’s Documentary (1994)
The first modern attempt to explore these underground mysteries came in 1994, when Turkish filmmaker Göksel Gülensoy produced the documentary Unknown Mysteries of Hagia Sophia. His team ventured into the submerged depths of Hagia Sophia, using diving equipment to navigate its flooded passageways.
Some of the most intriguing findings from his exploration included:
- Submerged tunnels and corridors, seemingly leading toward Topkapı Palace.
- Sealed-off passageways, hinting at a once-extensive underground network.
- Byzantine-era structures, suggesting that these tunnels may have played a role in the city’s history.
The documentary sparked curiosity worldwide, leading to further investigations in the following years.
🎥 Watch the full documentary here: Göksel Gülensoy’s 1994 Documentary
Scientific Mapping – Dr. Çiğdem Özkan Aygün’s Research (2005-2009)
Following Göksel Gülensoy’s initial exploration, scientific research teams set out to systematically map the underground tunnels of Hagia Sophia. One of the most significant projects was led by Dr. Çiğdem Özkan Aygün from Istanbul Technical University (ITU) between 2005 and 2009.
Using ground-penetrating radar, sonar technology, and historical documents, her team mapped out an extensive network of cisterns, underground galleries, and tunnels.
What They Found
- A complex labyrinth of tunnels beneath Hagia Sophia.
- Subterranean connections to key historical sites, including:
- The Hippodrome of Constantinople (Historical Map)
- The Basilica Cistern, located just 150 meters away.
- Possible links to Topkapı Palace, where Byzantine emperors once ruled.
- Chambers and flooded sections that remain inaccessible to this day.
This was the first scientific mapping of Hagia Sophia’s underground world, confirming that beneath its walls lies an intricate hidden structure—but not necessarily lost treasures or secret escape tunnels.
🎥 Watch a discussion of Dr. Aygün’s research here: Hagia Sophia’s Subterranean Labyrinth
📜 Explore ITU’s official research archive: Istanbul Technical University’s Project Page
Controversy & Legal Disputes Over the Tunnels
As interest in Hagia Sophia’s underground world grew, a legal battle erupted in 2009 between the two key figures behind its exploration:
- Dr. Çiğdem Özkan Aygün (scientific researcher)
- Göksel Gülensoy (filmmaker and documentarist)
The Lawsuit & Media Sensationalism
Dr. Aygün sued Gülensoy for releasing unauthorized footage of the tunnels, claiming it misrepresented her research and fueled misleading conspiracy theories. The lawsuit intensified speculation, with media outlets publishing wild claims about:
- Hidden Christian relics buried beneath Hagia Sophia.
- A lost Byzantine emperor’s tomb sealed off for centuries.
- Secret passageways leading all the way to the Bosphorus Strait.
Academic Rejection of Myths
Prominent historian Prof. Dr. İlber Ortaylı dismissed these rumors as historical fiction. He argued that while Hagia Sophia’s underground structure is impressive, many of the legends surrounding it are sensationalist exaggerations.
📖 Read more about the lawsuit and academic debate:
- Hagia Sophia Underground Research – ITU Official Page
- Prof. Dr. İlber Ortaylı on Hagia Sophia’s Historical Accuracy
Dan Brown’s Inferno & The Global Hype
In 2013, best-selling author Dan Brown brought Hagia Sophia’s underground tunnels into the global spotlight with his novel Inferno. The book, which follows a cryptic historical mystery, used Hagia Sophia’s subterranean legends as a key plot element.
How Inferno Fueled the Myth
- The novel suggested that Hagia Sophia’s tunnels contained hidden secrets, including ancient artifacts and underground passageways.
- After the book’s release, tourists flooded Istanbul, eager to explore the very locations described in the novel.
- Interest in underground Istanbul skyrocketed, even though historians and archaeologists continued to debunk many of the more sensational claims.
🎥 Watch a breakdown of Dan Brown’s Istanbul inspirations: Inferno & Hagia Sophia
📖 Read about Inferno’s impact on historical tourism: The Sun – Dan Brown’s Inferno Effect
Recent Discoveries – Do the Tunnels Go Beyond Hagia Sophia?
Recent archaeological digs and historical research have revealed that Hagia Sophia’s tunnels may not be an isolated underground network, but rather part of a much larger system beneath Istanbul.
What New Research Suggests
- Some newly discovered tunnels extend beyond Hagia Sophia, leading towards the Grand Bazaar, Basilica Cistern, and Topkapı Palace.
- Excavations suggest that some passageways may even lead towards the Princes’ Islands, a collection of islands off Istanbul’s coast.
- These findings suggest that Hagia Sophia’s tunnels may have once been part of a Byzantine-era underground transportation and water system.
🎥 Watch a recent documentary on Istanbul’s underground tunnels: Hagia Sophia & the Subterranean Network
📖 Read the latest findings on underground Istanbul: Hagia Sophia Research – ITU
Conclusion – Myth or Reality?
So, are Hagia Sophia’s underground tunnels truly a hidden mystery, or are they simply part of a fascinating historical structure?
- The tunnels are real, but the most extreme myths—hidden treasures, lost emperors, and escape routes—lack strong evidence.
- Archaeologists continue to uncover new sections of Istanbul’s underground, but most findings support practical functions like water storage, transportation, and connectivity rather than secret conspiracies.
- The true treasure of Hagia Sophia lies not in hidden tunnels, but in its unparalleled historical and architectural significance.
What do you think? Do these tunnels still hold untold secrets, or have the myths been exaggerated?
References & Further Reading
- Hagia Sophia’s Underground Research – Istanbul Technical University (ITU)
- Göksel Gülensoy’s 1994 Documentary – YouTube
- Dr. Çiğdem Özkan Aygün’s Research – YouTube
- Hagia Sophia & Subterranean Networks – Documentary
- Dan Brown’s Inferno & Hagia Sophia – YouTube
- Prof. Dr. İlber Ortaylı on Hagia Sophia’s Historical Accuracy – YouTube