Patkâné , Based on Pirnia’s definition is formed out of tiers of niche. Each tier is projected and extended farther out from the course bellow. Development of this element has led to conformation of one of the most interesting and complicated vaults in Persian architecture that mostly is not known as a single vaulting type due to its similarity to some other ones. This paper arranged to answer a fundamental question that “What is the essence of Patkâné as a vaulting type? To answer this question, the paper reviews the historical background of formation of Patkâné through referring primitive cases. Consequently, data about these cases is gathered through “Direct observation” and surveying of selected cases, “in-depth interviews” with contemporary traditional architects (Masons) and studying limited available written references. Then, formal and structural geometry of the cases is presented by the means of preparing 3D-Model of their structure and architecture. And finally, comparing and analysis of findings through a descriptive-analytic method result in achieving to a deeper understanding about essence of Patkâné and its elements. Accordingly Patkâné since its appearance is relative with the concept of creation of squinches in dome chambers of pre-Islamic architecture. In the next era development of technical science of Muslim architects led in the formation of ribbed arch which was covered by to niches. This structural element applied in four corners of transitional zone of dome chamber as a promoted solution. Finally, in the mid of the fourth century combination of ribbed arches in different levels resulted in formation of stratified space under the ribbed arches and consequently horizontal and vertical development of niches. This made a single new vaulting type which can be called as Patkâné.
