Beneath Hagia Sophia, Ancient Roman Passages Are Opening

A stone passage sealed for centuries beneath one of the world's most famous landmarks is coming back into view. At a presentation in Istanbul on October 17, 2026, Professor Hasan Firat Diker showed what his research team has uncovered beneath Hagia Sophia: about 170 meters of underground route cleared of debris, linked to a fifth-century Roman street that once ran past the site, along with a mud-filled burial complex older than the church itself.

The passages are only part of a wider underground world that is just now being documented. The team also re-excavated a hypogeum, a buried chamber complex with four adjoining rooms first found in the nineteen-forties. The monument standing today is the third church to occupy the spot, and the foundations of the first lie about two meters beneath the current floor.

A Timeline of What Lies Beneath

The layers read like a short history of Istanbul itself. The present building was raised under Justinian I in the sixth century, and it has served as a cathedral, a mosque, a museum, and again a mosque across nearly 1,500 years. Its underground infrastructure changed with each era: according to Diker, the tunnels carried water and air, and the longest one may run well beyond the building.

The modern story of the tunnels has its own timeline. In 1943, Schneider and the Byzantine Institute of America documented the underground passages; three years later, Muzaffer Ramazanoglu found the four-chambered hypogeum in the northeastern section, its rooms packed with mud. Diker's team surveyed the site again in 2017, and cleaning work that began last year exposed connections nobody had recorded. A study published this year in the journal Open Archaeology describes the newly revealed structures beneath the building's former atrium, including vaulted passages that had been sealed behind collapsed debris.

The scale of the work is hard to picture from above ground. Archaeologists removed three thousand tons of debris from the tunnels, as reported by europesays, and cleared the upper and lower sections of the burial complex, excavating a further one and a half meters beneath it. "This area is older than Hagia Sophia," Diker said at the presentation, explaining that the chambers had been filled with mud long before the church rose overhead.

How Long Are the Tunnels, Really?

In mid-September, Turkey's culture minister Mehmet Nuri Ersoy said the accessible passages are part of a far larger network, with sections described as stretching roughly nine kilometers. Some English-language headlines went further, reporting nine kilometers of tunnels as confirmed fact. But the minister's wording was careful: he spoke of sections "being spoken of" as reaching that scale, while noting collapses and blocked stretches that prevent passage.

His actual announcement was modest: cleaning and restoration continue in the reachable sections, and safe passages might one day open to visitors once the work is done. "However, there are collapses and areas that prevent passage," he said in a social media post, reported by basilica.ro. "We are currently continuing cleaning and restoration work in the accessible sections. Once the work is completed, we can consider opening suitable and safe sections to visitors."

The distinction matters. In 2022, Diker was discussing roughly one kilometer of documented accessible features; by this year, clearing had revealed new connections and previously unknown rooms. The minister's figure may describe the estimated scale of a wider system rather than a surveyed total — a point that analysts at thehistoriesfiles also raised when they traced how the claim traveled from a passive remark to a confirmed headline. Diker has long pushed back against legends of secret escape tunnels, calling the story unsupported since 2022. What is confirmed is smaller than the legend but arguably more interesting: a working water and ventilation system, repurposed across centuries, that is only now being mapped in detail.

What Happens Next for Visitors

Travelers should not plan a tunnel tour yet. The underground sections have not been announced as open, according to ad-hoc-news, and a Scientific Board is still studying which sections could safely receive visitors. The team is considering an exhibition of the archaeological remains once suitable areas are made safe, but no opening date has been announced, and the research areas beneath the monument are not ordinary sightseeing routes.

The restoration timeline hints at the pace. Exterior facade work is expected to finish by the end of 2027, after which crews could turn to the lower levels and hidden sections. Meanwhile worship and visitor access continue above ground, as they have throughout the restoration. For a building that survived fires, riots, and two rebuilds, the slow excavation underneath fits the place: history here is measured in layers, not headlines.

For travelers, the find is a reminder that the landmarks we photograph are only the visible part of the story. Other destinations are rethinking how visitors move through their icons too — Japan, for instance, is adjusting its tourist taxes as crowds reshape how trips work. And the appetite for big cultural moments shows no sign of fading, with landmark venues still drawing enormous crowds for museum galas and exhibitions. Beneath it all, the ground keeps its own records — and in Istanbul, they are only starting to be read.

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