Investigation on modern history of urban planning in Iran shows that there are three approaches in the subject under discussion: “Modernism and Westernism”, “Traditionalism and anti-Westernism”, and “Adopt and Adapt”. Proponents of the first approach believe in encouraging methods to use the external concepts. The second, is the idea about ​​cultural and religious values, ​​thereby everything with nontraditional orientation is rejected. In the third approach the thinkers believe that if the parts of tradition are synthesized by modernity, culture and religion can adapt themselves with the development. The purpose of this study is to evaluate the adaptation of traditional urban design patterns of Islamic-Iranian cities in incompatible district of new Iranian cities (spontaneous settlements) and to focus on the application of the third approach in the current situation of Iranian cities. On this basis, the method of comparative analysis has been applied to survey the differences and similarities between historical districts and spontaneous settlements. Studies show that there are rather similarities among physical - spatial parameters (such as structural and environmental criteria) between the two types of districts; because both of these residential districts formed as organic structures that are unstable against unexpected risks and earthquake. However, there are the differences between these two types of districts in organized and formed periods. Despite historical districts that have been consolidated and organized during hundreds of years, spontaneous urban textures formed quickly and without any plan and planning. Meanwhile, the historical districts have usually integrated townscapes and unique materials such as clay, bricks or stone, while this character (integrated townscape and unique materials) never have been seen in the spontaneous settlements. There are similarities in economic and socio- cultural characteristics between residents in the two the types of districts. The residents living in poor economic condition, but under a very strong socio-capital and traditional beliefs; There can be seen several socio-cultural and particularly religious characteristics in people of historical residential districts that are similar with the spontaneous residential places, such as “strong relationship among families, friends”, “hospitality”, “mutual relationship among family members”, strong religious beliefs and the needs for privacy and security. However, these communities are different in some principles such as quality of life and spatial and physical qualities especially in favorable and beautiful urban landscapes. So it can be extracted and adopted excellent principles from traditional and historical districts and adapt them to the inappropriate modern urban districts. With regard to the existence of these similarities, we explain applicable principles of the spatial characteristics and designing quality in the historical district of Yazd to apply in Baghshater District in Tehran as a spontaneous settlement. Findings show that we can use several solutions to reconstruct this zone included: 1) land readjustment as the suitable solution in Baghshater District with regard to the familial residential pattern in historical zone of Yazd such as Fahadan District. 2) Focusing on the traditional concept of mutual relationship in residential houses. 3) Emphasizing on the hierarchy of The entrances and exits of the residential units.