Brick vaults and burial chambers mark Hagia Sophia’s hidden historic layers in these file photos.
Restoration work at Istanbul’s 1,500-year-old Hagia Sophia is continuing with the aim of opening parts of its previously inaccessible underground tunnels, chambers and burial structures to visitors, Culture and Tourism Minister Mehmet Nuri Ersoy has said.
Ersoy said the ongoing restoration covers the landmark’s entire structure, including its underground network, where extensive cleaning, documentation and preservation work is being carried out. “We are conducting the most comprehensive restoration, conservation and reinforcement work in the history of the Republic at Hagia Sophia,” Ersoy said.
Work on the main dome is continuing, while reinforcement measures are also being implemented on the semi-dome above the eastern section, which houses the mihrab — the niche in the wall of a mosque that points toward the direction which Muslims face when praying — and minbar — a pulpit in a mosque from which the imam delivers sermons. Structural modelling and static analyses showed that this section required strengthening, he said.
Considerable progress has also been made beneath the historic landmark. Since February 2025, approximately 3,000 tons of mud and debris have been removed from underground tunnels, vaults and other historical spaces, allowing experts to examine areas that had previously been inaccessible.
The underground structures are also providing clues about Istanbul’s historical water management and infrastructure, including systems used for rainwater drainage and water distribution. Some passages are large enough for people to walk through, although researchers have yet to establish the full functions and historical connections of the entire network.
Ersoy also highlighted a four-room underground burial structure in Hagia Sophia’s northeastern section, known as a hypogeum, saying it could help shed light on traces of periods predating the construction of the monument.
“Our goal is to make suitable sections of the underground areas accessible to visitors as well, once the necessary conservation and safety measures have been completed,” he said, adding that exhibition and presentation plans for potentially accessible areas are being evaluated. He stressed that scientific assessments and safety requirements would determine which sections could eventually be opened.
The Byzantine-era structure was built between 532 and 537 during the reign of Emperor Justinian I and has served as a church, an Ottoman imperial mosque, a museum and, since 2020, a mosque again.
Three-stage plan for Formula 1
Ersoy also outlined a three-stage strategy for Türkiye’s planned return to the Formula 1 calendar, describing the event as an opportunity to promote Istanbul and the country internationally and generate tourism revenue beyond the race weekend.
The strategy will cover the periods before, during and after the Grand Prix, with the aim of encouraging international visitors to extend their stays in Türkiye. “We do not see this organization as an event limited to the race weekend. We consider it a major international communications opportunity for the promotion of Türkiye and Istanbul,” he said.
Ersoy said visitors could, for example, spend their holidays in the Aegean region before traveling to Istanbul to attend the race.
