عنوان مقاله [English]
Close relationship between religion and burial architecture and the special respect and reverence of the holy shrines for Muslims were the main reasons for development of burial architecture. Thus, the structure of such constructions has symbolic values and is associated with holiness, religious and political identity of the deceased person. Various types of domes such as rok, nar, and double-shelled have been introduced to the world. Ourchin dome, which has typical characteristics of the tombs in southern part of Iran, has not been studied. Little information about this type of dome is available in the history of Iranian architecture. The existing information, a few names and dates of constructing, is limited to some reports and pictures provided by foreign tourists and unknown writers. Therefore, the origin and the reason for developing such domes as well as their role are still mysterious. Discovering the methods of construction, the design strategies, and identification of different types of dome, as well as their related issues have been of special interest to the Iranian architects. In Achaemenid period, the rich emperors of Iran supplied the structure of their palaces with resistant woods from trees such as cedar from Lebanon or other far away countries. Therefore, due to poor economic conditions, the need to spend a lot of money to provide wood, the absence of good climatic conditions to grow these types of woods in jungles and plains, and the availability of soil, curved arches and domes found their place as continental and structural phenomena in Iranian architecture. In Sassanid period, the construction of domes blossomed and became so prevalent that the structure and construction method of the dome covering has been being used as the general model and instruction until now. The double-shelled vacant, double-shelled completely gaped, nar, rok, the combination of nar and rok, and ourchin domes could be abundantly found in Iranian architecture. Ourchin domes are only found in south-western part of Iran. Even in that part, they are scarce, because this style of constructing the dome is different from that of the northern and central parts. This is exclusive to Iran and only a limited number of this type of dom is found in Iraq. This very point indicates the uniqueness of this style of architecture. On the top parts of the dome, the consistent set-backs of the structure are located beneath. Normally, the height of the ourchin dome is much more than the other types. Consider the vertex of a triangle on Shushtar and its base line drawn from khark to Boroujerd, the places in this triangle feature mozaras domes. Many foreign tourists who have seen mozaras domes called them Pineapple Domes or in French Dome Aveols. This type of dome was only built as a tomb or grave. The methodology of the current study is descriptive and analytical. In different parts of the study, comparative, retrospective, and fieldwork studies have been used. The root of the word, ourchin dome, and its meaning are pointed out. Also, the origin of the Iranian architecture, which dates back to the Seljuqid period, is introduced. Then, the geometric relationships of its sides are examined and different varieties of this dome [star and polygonal] are drawn. Studying the typology of the examples of this dome in Iran and Iraq revealed some remarkable points about their geometric height and shape as well as the number of the floors. It was concluded that that the main reason for developing the general structure of this type of dome was symbolic and not just religious. This dome, on its own or in combination with religious places, has played an effective and functional role over time.