An Investigation of Astronomical Features and Calendric Function in Jayy City and the Palace of Sarvestan

Document Type : Research Paper


Department of Architecture, Ramsar Branch, Islamic Azad University, Ramsar


According to available documents, architects in the past were not only equipped with their"normal" knowledge of traditional architecture, but were also armed with astronomical rules; and co-operated with astrologists in designing of ancient buildings and cities. According to some records, various samples of solar considerations have been made while building fire-temples, palaces and circular cities in the Sassanid era; as it is possible to detect the time of seasons changing by sun's radiation upon definite apertures and gates at the time of sunrise and sunset. Lack of necessary information to recognize the astronomical characteristics of monuments and sites, impedes their restoration and reorganization to reach the desired results; and perhaps unconsidered repairs and manipulations, eliminate the possibility of presentation and revival of ancient astronomical architecture tradition on them.
In this paper the existence of some solar-astronomical considerations in construction of ancient city of Jayy, as well as a monument known as the palace of Sarvestan has been surveyed. Although the circular city of Jayy has been lost completely, the astronomical features of its enclosure have been reconstructed within a model based on primary sources (Interpretive-Historical Research Method). Even the locations of its four gates have been determined exactly. Therefore, it has been attempted to answer one of the key questions concerning the geography of Isfahan and its borders in ancient times. In traditional view it corresponds with the so-called district of Shahrestān. According to findings of present research, however, the actual location of the ancient city of Jayy has been at the north-western side of the Buyid enclosure constructed in Isfahan whose four gates were located in the four districts of modern Isfahan called as Dardasht, Jūbārah, Pāyīn-Darvāzeh, and Darvāzeh-Now.
Besides, by contemplating on the applied astronomical issues in architecture and causal thinking in architectural design the hypothesis of calendric function in the palace of Sarvestan has been explained; and to confirm the validity of hypothesis, the researcher has adopted field measurements and notes (Field Study Method) and on-site visual observation. Findings of this study demonstrate that the eastern gates and apertures of the major and minor domes of the palace of Sarvestan are being deliberately accommodated with the sunlight spot at the time of sunrise at the Equinoxes as well as the Solstices; and this explains the reason behind the 30 degrees declination of the longitudinal axis of the Sarvestan palace with respect to Magnetic North.
The author has addressed some historical reports indicating specific orientation of porches (ayvāns) of palaces and gates of Iranian circular cities and these reports are implying that they have calendric and astronomical functions. At last it is suggested that the eastern and western porches of the monumental complex (erbedistān) of Kuh-e Khvājeh in Sistan [from this viewpoint that they are probably located facing the sunrise and sunset positions at the Solstices] and the eastern gate of ancient cities of Gūr, Dārābgerd and Balkh [from this aspect that it is located facing the sunrise position at winter solstice] need more considerations and field studies.