Feasibility Study of Existence of a Dome over the Cruciform Palace of Bishapur in Sasanian Times

 Some architectural and artistic monuments have been preserved from the city of Bishapur, which was founded in the early Sasanian era by Shapur I. One of them is the remains of a building called the Cruciform Palace. The cruciform plan of the construction is surrounded by huge piers of stone and gypsum, about six meters thick, and its central square is over twenty-two meters long. There are currently no signs of ceiling or roof in situ.Hypothesis: The previous theories about the possible ceiling form of the Cruciform Palace of Bishapur are not based on documentation. The imagined dome over the central square of the Cruciform Plan would be the largest stone dome of that period in Iran. The existence of a dome above this building and its compliance with the conventional dome form of Sasanian architecture is the hypothesis of this research.

The purpose of this research is to find indications that demonstrate the possibility of the existence of the dome and then illustrate the possible authentic form of its structure based on the reliable evidences.

To achieve these goals, a comparative study method was utilized and the samples that were similar in structure, architecture, and historical style were studied. Their dimensions and proportions were examined to obtain a model for the size of piers and spans in the Sasanian domes.

According to the obtained results, the thickness for piers of the palace is consistent with the average size of the selected samples of the Four-Arches constructions in Iran and potentially confirms the existence of a dome over the square section of the cruciform plan. About the height of the dome, the range of results is various and the hypothetical height can be estimated based on the mean measurements.