<p>Architect works of various historical periods before be considered as a constructional issue is regarded as a mirror reflecting the way contemporaneous people has lived, and in traditional architecture of Iran, the buildings are indications for the old architectural culture of it, doubtlessly. One of the most noticeable characteristics of architecture of Iran is the Basic Principle (called Niyaresh Principle in Persian) that resulted in very stable buildings.&nbsp; Optimal utilization of accessible materials like soil, various designs and their harmony with the surrounding nature, and also stability of these arched structures for many years to the present era, instigate us to surveying their construction process, reasons for stability, and the occurred changes by the past of the time. One of the most stable elements of traditional architecture of Iran is the application of arched roof and tavizeh. In traditional constructions, tavizeh has a very important role as a weight force transferor due to its stable structure. Therefore it is aimed to surveying the conception of the tavizeh and its formation. Appearance, structure and implementation of tavizeh have been changed by the past of the time and from one place to another one, so that came in a definite form. Bricklaying method and as a result the reason of the stability of tavizeh(s) is a puzzle that is answered in this paper.</p>