Introduction and Typology of Geometric Decorations in the Architectural Ornaments of the Dome of Sultaniyya

The Dome of Sultaniyya is one of the most important monuments of the Ilkhanid era in Iran, which has an octagonal plan, eight minarets, and three sections including the dome chamber, turbat-khana, and the cellar. It is abundantly decorated with tilework, stucco, brickwork, etc. One of the key architectural ornaments in this building is geometric decorations that are applied either singularly or in combination with other designs or inscriptions. The purpose of this study is to introduce and derive the typology of geometric decorations used in the architectural ornaments of the Dome of Sultaniyya. Therefore, the main question here is to introduce geometric decorations in the architectural ornaments of the Dome of Sultaniyya and the introduction of their significant types. Data was collected through both field and library research following a descriptive-analytical method. The results of the study show that the use of geometric decorations is among the key types of decorations in this monument, seen in almost all parts of the building such as arches, wall surfaces, etc. These decorations consist mainly of intricate gerehs [lit., knots] and their integration with plant motifs and inscriptions. Different technical applications increase the complexity, variety, and beauty of these decorations. Most gerehs are based on six-, eight-, ten-, and twelve-pointed polygons, which make them exquisite and extensive. Also, the tradition of “transforming knotwork” is considered as one of the important types of decoration in this building.