Sivas Ulu Mosque is one of the oldest mosques in Anatolia, located in the city center of Sivas, Turkey. The structure was built in 1196–1197 during the reign of Kutb al-Din Melikshah by Kızılarslan bin İbrahim, and designed by the architect Kul Ahi. Due to its architectural style and historical context, it is considered one of the early examples of Anatolian mosque architecture.

^{Exterior View of Sivas Ulu Mosque (Sivas Municipality)}

Architectural Features

The Sivas Ulu Mosque has interior dimensions of 54.70 meters by 33.70 meters. It features a closed plan with no courtyard and a flat roof. The northern facade has three entrances—one located at the center and the other two near the corners. The interior space is organized into eleven naves running perpendicular to the qibla wall in a north-south direction. These naves are separated by 50 rough stone piers, which are connected by pointed arches. The central nave, aligned with the mihrab axis, is wider than the others.

Materials and Masonry

The mosque is constructed using cut stone and rubble masonry techniques. There is no prominent stone ornamentation; its plain façade reflects the architectural simplicity of its time. Decorative elements on entrance doors and walls are extremely limited.

^{Interior View of Sivas Ulu Mosque (Turkiye Culture Portal)}

Mihrab

During restoration works in 1955, the original mihrab (prayer niche) was uncovered. The mihrab features geometric decorations composed of two nested octagons with square patterns formed by extending lines from their edges. This decoration style aligns with the early Islamic period’s geometric ornamentation traditions. Above the mihrab is a seven-tiered muqarnas niche that narrows upward. No inscriptions or vegetal motifs are present.

^{Mihrab of Sivas Ulu Mosque (Turkiye Culture Portal)}

Minaret and Structural Tilt

The minaret of the mosque was constructed independently at the northwest corner of the building. Today, it displays a tilt of 117 centimeters, making it one of the notable leaning minarets. Due to this tilt, the General Directorate of Foundations has launched a comprehensive restoration project.

The restoration plan includes drilling down to the foundation level from inside the minaret using a core drilling technique, and reinforcing it with eight steel anchors. The project also aims to repair decayed parts of the structure, remove excess loads, and replace incompatible components without damaging the original fabric. The restoration will cover not only the minaret but also the mosque’s main structure, courtyard, and toilet facilities.

Cemetery and Ottoman Remains

On the mosque’s northeastern side, there is a cemetery (hazire) consisting of 23 Ottoman-era graves. This suggests that the mosque maintained its religious function over the centuries and that the surrounding area was regarded as sacred.

Historical Context

The mosque’s architectural characteristics and construction techniques have led some researchers to associate it with the Danishmendid period (1085–1178). In this context, it is compared with structures like Niksar Ulu Mosque (1145), Kayseri Ulu Mosque (12th century), and Yağıbasan Madrasa in Tokat (1151–52). Although the Danishmendids came under Seljuk rule in 1178, their architectural style persisted until the end of the century. Therefore, Sivas Ulu Mosque is considered a transitional-period monument.

Current Status and Conservation

The structure is protected by the Republic of Turkey Ministry of Culture and Tourism and the General Directorate of Foundations. In the 2020s, extensive restoration projects were launched. The building was digitally documented using FPV drones, and structural analyses were conducted to guide future conservation efforts. The main objective of the restoration is to preserve the mosque’s original structure and ensure its sustainable use in the long term.

^{Sivas Ulu Mosque Drone Footage (AA)}