From the very beginning of the genesis of theater, performing in “outdoor spaces,” has been one form of theater which includes squares, passageways, centers for people gatherings (such as, bazaars, in front of temples and farms) and other such spaces. In modern times, we witness theater and performances that are performed in outdoor spaces like streets, cafes and other “informal” theater spaces instead of being performed in “indoor” and “formal” spaces. Although there are similarities between the prior performances with the ones in ancient times, the outdoor performances and informal theater settings, usually knows as “street theater,” tend to maintain a distance from the aura of the ritual and focus on political, social, economical and even military issues. Usually these issues are expressed in terms of protest. One similarity between theater in ancient and modern times, is utilizing urban spaces (perhaps, in the case of ancient times, rural spaces) as a stage for performance. By utilizing urban spaces these theater performances transfer a new kind of identity to the city; they have an effect on the city and the city affects them reciprocally. Some researchers believe that the function of physical space is deeply based on its cultural roots. This fact could be seen in religious plays in primitive societies, old civilizations and even modern societies which have kept their religious traditions. Study about the social- cultural roles of physical space presents three facts: first, physical space reflects social- cultural desires of artists and audience. Second, this space has important role in society and social- cultural life of audience. And third, physical spaces of religious plays in old civilizations were among the most amazing parts of man’s architecture. Today, urban spaces are not merely understood as spaces for business and trade or material and physical support for every day livelihood, rather as evidenced by the arts that saturate the urban space and create a spiritual atmosphere (caused by art), the city can play a more important and higher role for humanity. To this day, different researchers inside and outside Iran have studied the topic of “street performance” or “street theater.” The common aspect in all these researches has been their emphasis on principles of performance for these kinds of theaters. Few people have looked at this topic through the importance of the urban spaces or “the city as the stage of performance.” In comparison with prior researches, this article’s special characteristic is its entry point to the topic i.e. from an “urban” standpoint. Furthermore, unfortunately, most of the books published inside Iran on this issue, are repetitions and copies of Western researchers and little signs of innovation and local identity of “street theater and the city” in Iran can be sought in them. The 20th century with its important changes in different aspects such as economical, political and social, has been a good context for creating street theatre. A large number of dramatists found this kind of performance suitable for connecting their productions to people. As a result many plays were produced in this genre. Among the most important dramatists, who paid attention to the street theatre, can be mentioned Antonin Artoud, who has come to this field with his idea of Group Theatre. In 1919, Oruonov had shaped street theatre in Russia. Besides Oruonov, PLATON Kerzhentzev and Vakhtangov also had the same experiences. In Italy, Odin Theatre, Barbaya Theatre, The Third Theatre and Darufo Theatre started working in this field. In France it was Peter Brook that had experiences to establish more relationship between actor and audience. One of the most famous groups in that era called Living Theatre was founded in 1946 by Judith Malina and Julian Beck. The most important issues used in this group were about fighting against war, especially in Vietnam. Open Theatre Group, founded by Joseph Chaikin and Happening Theatre Group, founded by Allan Kaprow, by focusing on environment and space as the key element of theatre made the American movement of street theatre faster. Richard Schechner established Performance Theatre Group in 1968 and also The Bread and Puppet Theatre Group was founded by Peter Schumann. Both mentioned groups had a great influence on street theatre in USA. Inquiring into “street theater” once more, this time from the perspective of the importance of urban spaces and emphasizing the usage of urban spaces as places for theater performance, due to the close relationship with the audience, the existence of potential audience and finally, the manifestation of themes that are closely related to peoples social lives, could offer new guidelines for Iran’s theatrical scene and transform theater into a serious art in people’s daily lives. Artists and people of the past had placed great attention to this point and in reality this has rendered this kind of theater a part of Iranian life.