The Hagia Sophia's underground network: A 1,600-year-old tunnel system revealed
The restoration of Istanbul's iconic Hagia Sophia has unveiled a hidden network of tunnels, offering a glimpse into the monument's ancient past. These tunnels, dating back around 1,600 years, were discovered during cleaning and survey work in the garden areas surrounding the structure, alongside a hypogeum, an underground burial complex. The find highlights the importance of scientific oversight in the conservation program, with the long-term safety of the building a key focus.
A hidden network from the early Byzantine era
Turkey's Culture and Tourism Minister, Mehmet Nuri Ersoy, emphasized the scale of the underground discovery, stating that seven tunnel lines were documented, and 1,068 tons of soil fill were removed during cleaning operations. Another 102 tons were removed from a separate underground burial area. The report also describes multiple underground 'spaces' and linked tunnels in the western garden and northern (Vezir) garden areas.
The tunnels' practical functions, as explained by Prof. Hasan Fırat Diker, help explain why they sit close to the structure's foundations and gardens. These systems are crucial for ventilation and water management, not romantic 'escape routes'.
Restoration and the underground context
The restoration work is not happening in isolation but alongside major efforts above ground, including scaffolding, façade cleaning, and structural checks. Minister Ersoy stressed the importance of scientific assessments and contemporary restoration requirements, a crucial consideration at Hagia Sophia due to earlier interventions using inappropriate materials.
The timing of the restoration also reflects a broader concern: Istanbul's earthquake risk. Engineers focus on vulnerable structural points while preserving the building's integrity. The underground work's logic often relates to load paths, drainage, humidity control, and foundation health.
A city built with water below its feet
Hagia Sophia's underground is part of a larger Istanbul reality, shaped by cisterns, conduits, and storage systems that once supplied palaces, churches, and neighborhoods. The present Hagia Sophia, built in 532-537 AD, has a history of repairs following earthquakes. This architectural life story makes hidden infrastructure essential for survival, as much as the dome above.
Nearby, the Basilica Cistern showcases Byzantine Istanbul's water management on a vast scale. Tunnel-like maintenance spaces around major monuments are plausible due to this ancient system. Researchers can now better understand drainage, humidity, and maintenance in different phases without relying solely on myths.
