Urban spaces are rich in memories that remain in the minds of residents as well as visitors. Memories are sometimes individual and sometimes collective, which shared by all citizens and members of society. Events in the city create memories and memories create lives. Those memory-making spaces, that previously existed in our cities, have been forgotten or qualitatively degraded, resulting in reducing the proper context for urban events and social interactions, and thereby the citizens’ sense of belonging to space. What makes urban spaces memorable is the objective and subjective instances of semiotic patterns. Today, signs have faded in urban spaces, and this has been an introduction to the amnesia of urban spaces. So, the signs are regarded as an important tool for the continuity and transfer of collective memories. In this regard, the present study aims to compare the memorability level of urban spaces. To this end, in the present study, it is attempted to extract the components contributing to the formation of a collective memory of urban spaces using a semiotic approach. Content analysis and deductive reasoning are the main methods of establishing the intellectual bases of the research. Confirmatory factor analysis is applied for statistical analysis using LISREL software. The results show that although at present, perceptual, social and semantic codes (perceptual-mental and social-temporal components) of the sense of collective memory have the most impact on the memorability of Hasanabad Square and Azadi Square. The perceptual and social codes have the highest effect in Azadi Square and Hasanabad Square, respectively which can be justified regarding the spatial properties of these two spaces (logical codes)