Research and studies on the natural archeological site of Pasargade, a world heritage, have mainly been directed towards archeological excavations and discovery of remnants. Its natural features, including the ancient lake of Pasargade remain in a veil of ambiguity. Determining the exact location of the ancient lake and the course of Polwar-Seivand River are valuable criteria in verifying the boundaries of Pasargade, and important factors in the formation of this valuable site. The objective of this study is thus, determination of possible existence of the ancient lake in the Marghab plain, and if proved, verifying the exact location of the lake basin. The research method consists of processing aerial photos and satellite data, using historical and archeological documents, and field studies. These methods helped provide the natural bed layers of the site comprising of geological, geomorphologic, hydro-geological, vegetative cover and climatic features. The research led to discovery of an ancient lake basin in the mouth of Bolaghi Gorge, and determination of the river course across the plain in the Akaemenian era. After proving the existence of a lake, and the natural bed features of the site in the Akaemenian era, the next question was brought up: Have the lake and river had any effect on the formation of Pasargade site, and the organization and distribution of its buildings? A second analysis of data, revealed the direct effect of the existence of lake and river on the spatial and structural relations of the scattered structures in the site, including the castles, ancient riverbed, Pasargade gardens, tomb, and especially the entrance to the palace.
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