1,600-year-old mystery solved: Turkish minister confirms 9-kilometer-long tunnel beneath Hagia Sophia

An urban legend about the existence of a vast underground network of passages beneath Hagia Sophia in Istanbul has received confirmation from Turkish authorities. The Minister of Culture and Tourism, Mehmet Nuri Ersoy, said that sections of the tunnel, with a total length of about nine kilometers, have been recorded beneath this historic building.

Ersoy, speaking at a press conference in Kahramanmaras, said work is underway to clean and restore the accessible parts of the underground passages.

As he stated, access to some parts is currently impossible due to collapses.

“Once the work is completed, we can assess the opening of suitable and safe parts for visitors,” the Turkish minister said.

His statement follows the announcement of February 2026, when Ersoy announced that tunnels dating back about 1,600 years had been recorded, reports Protothema.

The Turkish minister also spoke about the restoration, maintenance and static strengthening work at Hagia Sophia, declaring it one of the most comprehensive operations ever carried out at this building in the history of the Republic of Turkey.

The purpose of the work, as he said, is the safe preservation of the nearly 1,500-year-old building and its transmission to future generations.

According to his words, work on the restoration of the tombs, the Children’s School, the Clock Tower and the gallery floor, as well as the static strengthening of the northeastern minaret, has been completed.

In the main dome, work on structural strengthening and mosaic restoration is still ongoing.

“The temporary metal roof and protective covering system that protects the main dome have been completed. Thanks to a special platform built inside the building, work is being carried out to document, clean and conserve the mosaics in the dome, while at the same time religious activities and visits continue,” Ersoy said.

As he added, static analyses showed that it is also necessary to strengthen the eastern semi-dome. In that part, alongside the strengthening of the supporting structure, a new phase of work will begin for the preservation of the mosaics, painted decorations and marble surfaces.

Hagia Sophia, one of the most famous historic buildings in Istanbul, has changed its purpose several times over its nearly 1,500 years of existence and has gone through various phases of renovation.

Minister of Culture and Tourism Mehmet Nuri Ersoy: “There is talk of a tunnel network extending approximately 9 kilometers at the Hagia Sophia Grand Mosque. After the work is completed, we can consider opening it to visitors.” (in a post on X)