the cognition of the city at night

human presence and accordingly establishing suitable condition for social interactions are important factors in shaping urban spaces. caring to different aspects of improving environmental qualities especially perception aspect and ease of perception from the environment with legibility improvement is an element that was emphasized from the base of urban design. the role of time, commence of day and night and its effect on perception and legibility of the environment have not been investigated deeply. although time effects the level and the way of perception and legibility and it should be noted that there is clear difference between human perception and space legibility during day and night.this research is looking for effective major factors on urban spaces qualities in day and night with descriptive and comparison method on the case studies and their images of zanjan and abadan cities and tries to approve the differences of these images. results of performing this research clearly approving that, social, functional and perceptional dimensions are the most important dimensions of improving space quality at night. it should be declared that there are a lot of differences between the images and the perception of the city during day and night. in addition, the mention priority to urban five elements in shaping these maps are differ either.