Unveiling the Enigmatic World of Istanbul's Subterranean Treasures

Underneath Istanbul — the city that bridges continents and intertwines multiple histories — lies a hidden world that echoes with the whispers of centuries past. With its myriad layers of civilisations, not only has Istanbul left its mark on the surface, but also etched its story deep under it.

Amateur historian Arzu Ulas embarked upon a remarkable journey of discovery in 2018. Through a meticulous examination of thousands of Ottoman era documents, she sought to uncover the hidden gems of Istanbul's underground realm.

This subterranean realm, concealed from the eyes of everyday passersby, unveils an awe-inspiring tapestry of artefacts, from grand cisterns that once quenched the thirst of empires, to secret tunnels that cradled the ambitions of conquerors. As we descend into the depths of this mesmerising labyrinth, we embark on a journey through time, where Istanbul’s underground treasures beckon us to discover the mystique of their existence.

Voyage to Byzantium

Founded in the 7th century BCE, Istanbul stands as a testament to the enduring passage of time. The city that harks back to both the Byzantine and the Ottoman periods, holds a place of honour among the world's most treasure-laden metropolises. Its streets and landmarks bear witness to the passage of centuries, but the city's riches extend far beyond what is visible. Beneath the bustling streets and historic edifices lies a hidden realm, an underground tapestry that weaves together millennia of history. Here, beneath the surface, lie cisterns, cellars, aqueducts, archaeological relics, and an array of structures that house the secrets of eras long gone.

This subterranean world is nestled within the region now known as the "historical peninsula”, framed by the serene waters of the Golden Horn to the north, the majestic Istanbul Strait to the east, and the expansive Sea of Marmara to the south.

In the 16th century, an imprisoned European captive found himself in this enchanting city at the heart of the Ottoman Empire. His observations, penned with awe and wonder, painted vivid pictures of this remarkable place. Among his descriptions, one particular feature stood out — a cistern that seemed to defy imagination. He wrote, "Marble columns reaching skywards, supporting the ceiling of vast chambers constructed entirely from stone bricks. These chambers, so expansive that one could easily explore their grandeur, boasted towering ceilings that spared one the need to stoop. A labyrinth of columns divided the interiors into narrow, winding streets, creating an underground world of captivating mystery."

This cistern, known as the Basilica Cistern, but often referred to as the "Sunken Palace" or "Yerebatan Sarnici" in Turkish, is a renowned attraction in present-day Istanbul. Alongside it stands the Binbirdirek Cistern, another architectural marvel that has captured the imagination of countless visitors. However, captivating as they are, these two cisterns represent only a fraction of the subterranean wonders concealed beneath the surface of this ancient city.

National Treasure: Book of Secrets

Ulas’s quest is twofold: to pinpoint the locations and current condition of 302 subterranean structures within the historical peninsula, and to descend into their depths as an intrepid miner, to witness these treasures firsthand. In the process, Ulas also authored a monumental work spanning around a thousand pages, Istanbul's Underground Structures in the Light of Ottoman Documents.

“My pursuit had a dual purpose,” she tells TRT World. “First of all, I hoped to address the gaps in historical literature, particularly regarding the Ottoman period. Also, and perhaps more profoundly, I sought to bridge the gap between the distant past and the present day.”

Ulas aimed to answer a tantalising question: Did the places described in documents written during the 17th, 18th and 19th centuries, detailing these hidden locations, still exist in the bustling modern city? Her mission was not confined to documentation; she yearned to breathe life into these moth-eaten words, to provide insights into the physical states of the wonders they described. Through her exhaustive research, she arrived at a profound revelation — underneath the layers of Istanbul's vibrant streets, lay another city, an enigmatic world of history and mystery.

Raider of the Lost Ark

Her research led her to identify 198 structures that continue to endure till the present day. Among these were 95 cisterns, 35 cellars, 15 aqueducts, 5 mausoleums, 11 wells, 11 holy springs, 5 sunken fountains, eight fire pools and three sites of archaeological remains. Not only did these hidden gems hold historical significance, but also practical importance.

The city's subterranean structures, including cellars that once stored essential provisions, played a pivotal role in sustaining its military, commercial and social life, while fulfilling the needs of its citizens. Among these treasures, the Ottomans held two dearest. The first was the state archives, safeguarding the memories of their quotidian lives. Legends whispered of a place where these precious documents were stored when Istanbul was conquered in 1453 by Sultan Mehmed II (known as Fatih Sultan Mehmet) — the Yedikule Cellars. The second was the State’s wealth, carefully preserved within the cellars of the majestic Topkapi Palace.

As the shadows of time stretch across the pages of Istanbul's history, Ulas' quest to unearth these subterranean wonders stands testament to the allure of the city's hidden depths. It is a reminder that beneath the bustling streets and amidst the echoes of the past, another world, of intricate marvels and untold stories, awaits those who dare to venture beneath the surface. Istanbul, with its rich tapestry of history, continues to unveil its secrets, one layer at a time, beckoning explorers to discover the wonders that lie beneath.