After decline and fall of the Parthian dynasty by Ardeshir Babakan in early third century, the new dynasty, called Sasanian, rose. The quantity of the remained of the Sasanian dynasty in compare with the Parthian shows that construction activities such as building bridges, dams, castles and cities are considerably developed. Establishment of many Persian ancient cities is attributed to the first two Sasanian kings, Ardeshir and Shapour. Most of these cities are constructed on a band which is spread between the Persian Gulf and Zagros mountains. This band connects the Strait of Hormoz to Mesopotamia and finally to Ctesiphon. The city of Bishapour is constructed by Shapour’s order in a location where the Zagros Mountains have the minimum distance from the Persian Gulf. This research is about the urban geometry of Bishapour as a milestone in the history of Persian urban design that is based on field works and library studies. The cultural and governmental evolution from Parthian to Sasanian dynasty, such as tend to concentration, is assessable in the changes of the urban constructing methods. Shahre-Gour and Bishapour are indicators of the new cities which were designed on base of the point of view of the Sasanian ancestors. Shahre-Gour presents the symbol of an urban design approaching to power and Bishpour indicates the period of settlement and stability, with similar attitude. One of the urban research methods for these cases is to study and analyze their main geometry and the relationship between the natural topography and their urban design is the most important. Bishapour is a symbol of benefit of natural features besides the regular geometry. The employment of perpendicular axes had been the principle concept of Bishapour. The other important employed rules in urban design of Bishapour are symmetry and concentration to a point which are benefited in various scales.
