analyze the functional performance of the urban spaces in Cairo′Down town (Attba Square) and historical cairo (Moaz Eldin street) and its effect upon economical, political, social , cultural life of the society and people behavior by studying the universal adopted principles and criteria in this field. According to that, analytic study define a functional requirements, which could contribute to reach a criteria for evaluating the functional efficiency of the urban spaces in the Cairo′Down town and Moaz el din street. The research depends upon different criteria for successful urban spaces including uses&activities-Accessibility-Comfort&image-Sociability and-Economically in order to determine the range of  realization. Study concludes a set of results that define and describe the functional performance of the urban spaces in the Cairo′Down town and Moaz el din street and its effect upon people behavior. Finally, study propose some recommendations that could contribute  to treat the weaknesses  and promote the strengths in the process of the urban spaces formation in the following areas(Attba Square and Moaz Eldin street) for future development.