Restoration work is continuing at the 829-year-old Ulu Mosque, one of the best surviving monuments of the Seljuk period, under a project launched by the General Directorate of Foundations of the Culture and Tourism Ministry.
As part of structural reinforcement efforts inside the mosque, construction has been completed on 30 of the planned 50 columns, with work ongoing on the remaining 20. In the next phase, leveling works will be carried out in the interior and stones incompatible with the building’s original fabric will be replaced.
Recent measurements have shown that the mosque’s minaret leans 116 centimeters from top to base. Steel scaffolding has begun to be installed as part of surface restoration works. The project is scheduled for completion by the end of 2027.
Mehmet Ali Çalışkan, regional director of foundations in Sivas, said the restoration of the Ulu Mosque, one of the oldest and most distinguished mosques of the Seljuk State, is ongoing.
He noted that the mosque was built in 1197 and has survived to the present day, adding that restoration works began on July 25, 2025, under a protocol between the Regional Directorate of Foundations and the Sivas Ulu Mosque Foundation.
“The oldest original and still-standing part of the structure is the minaret. It is observed that the minaret leans 116 centimeters off the vertical axis. This may be the most comprehensive and distinctive restoration ever undertaken in Türkiye,” Çalışkan said.
Süleyman Çoban, head of the Department of Artworks and Construction Works and the project coordinator, said preparatory work for the restoration project began in 2020.
He explained that an academic study had been conducted to determine whether the minaret poses any structural risk or future danger.
“As part of this study, we took samples of the stone, mortar and bricks used in the minaret and subjected them to laboratory tests and structural performance analyses,” he said.
Çoban emphasized that the movement of the minaret has remained stable and within its limits, showing no ongoing displacement.
“Structurally, the minaret is in good condition. Its main issue is the 116-centimeter deviation from the vertical axis between the balcony level and the base, indicating a significant lean,” he said.
Following laboratory analyses, the team created a three-dimensional profile of the minaret using laser scanning and modeled it with advanced engineering software to assess whether reinforcement was necessary.
“The findings show that the minaret would collapse in an earthquake of magnitude 7.5. To prevent this, we have developed a reinforcement project. Using non-destructive methods, we will install stainless steel elements from the balcony level down to beneath the foundation, which will make the structure more resistant to lateral seismic loads,” he added.
Çoban also noted that detailed data had been obtained regarding the minaret’s foundation, which extends approximately six meters below the mosque’s interior floor level and includes juniper piles, indicating a robust original construction.
In addition to structural reinforcement, surface restoration will also be carried out on the minaret.
