Physical Transformations in the Tomb of Imamzadeh Abdullah in Shushtar: A Manifestation of Iranian Architecture in the Transition from the Seljuk- Khwarezmshahi Period to the Ilkhanate Period

Due to its large number of mausoleums and tombs, Shushtar has become a treasury of Islamic architecture, among which the building of Imamzadeh Abdullah is a significant point of interest due to its construction period (transition from Seljuk- Khwarezmshahi period to Ilkhanate period), structure form, type of dome, the historical precedent of the dome as a pioneer in Iranian architecture, architectural features, decoration and diversity of inscriptions, which indicate the importance of this building. Religious buildings are usually ousted gradually from their original form due to the abundance of renovation, reconstruction, and expansion. The current research is performed to study and review the tomb formation and extension and identify its formation ideas, original plan, building extension, and architectural history.

This research, performed using a descriptive-comparative-analytical method, is fundamental in terms of purpose. It is considered qualitative research in terms of the data type and regarded as historical research in terms of available data. Data collection tools include the direct observation of physical and spatial components, the building position, and the examination of documents that provide information on the subject of research. Qualitative data analysis methods were also used for data analysis.

The tomb, which was far from residential areas not long ago, is now located within the urban fabric of Shushtar with the extension of urban spaces. Due to the natural shape of the terrain, it is placed at a higher level than the surrounding area. The complex has an area of ​​700 m2. It consists of the entrance facade, the side dome, the corridor between the two domes, the main dome, the tomb of Bibi Gozideh Khatoon, and the surrounding spaces such as the women’s prayer hall portico, porch, and two minarets.

In contrast to previous studies, which were brief, inconclusive, and at times erroneous in descriptions, disregarding the evolution and physical extension of the building, the present study seeks to address new issues such as the original building structure, building development from a single building to a tomb complex within different periods, the origins, emergence, and continuity of construction, structure and decorative patterns of the complex during the transition from Seljuk-Khwarezmshahi period to the Ilkhanate period. This study also studies the influential role of the building in Iranian architecture and the tomb architecture in particular. The original body of Imamzadeh Abdullah, which was formed before the rule of the Ilkhanate and during the Abbasid caliphs over Shushtar, consisted of a single dome with a vault.The construction model, plan, architectural style, especially the stepped dome and its overall spatial structure, rather inherit the architectural style of the tombs from Iraq and Mesopotamia than those of Seljuk-Khwarezmshahi architecture. Despite some unknown features of the building, many of the dome details and decorative features are simply influenced by the common patterns of Seljuk, Kharazmshahi buildings, and the indigenous features of the region, to some extent. As a rare example of the combined style of pre-Mongol Iranian architecture (Seljuk-Khwarezmshahi period) and Iraqi architecture, this dome has, on the one hand, influenced the construction style of domes and spatial structure of tombs in the south and southwest of Iran, especially single domes. On the other hand, it misses links from some decorative features within the architecture of the Seljuk-Khwarezmshahi period, such as plastering and tiling, to the Ilkhanate period. According to the written sources and field studies in Ilkhanate period monuments (8th century AH), the building has turned into a combined tomb-monastery complex through some constructions and renovations. The side dome is among rare surviving monuments. Most of the renovations and extensions have occurred during the Safavid period. At this period, many physical changes were made in the original spaces, such as the main dome and vault. On the other hand, the tomb was transformed into a large burial complex by the allocation of endowments and building spaces such as the entrance façade to the side dome, surrounding landscapes of the building, guest house, school, residential rooms, and the huge entrance structure. In the Afshari period, two minarets were added to the building. In the Qajar period, some decorations were embedded, and finally, with the changes made in the contemporary period, the complex has shaped into its present form.