This paper analyses the aesthetics of urban scenes, characterized by different levels of order and visual stimuli, through visual perception of users of Porto Alegre. It follows an investigation regarding the dichotomy between the philosophical and the empirical aesthetics approaches, as well as the impact of formal aesthetics. The existence of differences between the aesthetic responses of architects, non-architects college graduates and non-college graduates is also examined. Still, the reasons for the assessments conducted by these three groups are identified. Considering the environmental aesthetics approach, evaluations of urban scenes with varying degrees of harmony and visual stimuli may provide additional knowledge concerning the dichotomy between philosophical and empirical aesthetics. Data was collected through questionnaires and interviews conducted with 60 architects, 60 non-architects college graduates and 60 non-college graduates. Questionnaires and interviews were complemented by a photographic kit consisting of 3 A3 sheets, each sheet with 3 street scenes. A sample of the street scene consists of scenes of contemporary buildings in Porto Alegre (3 scenes) and historic buildings in Porto Alegre (3 scenes), Prague (1 scene) and Florence (2 scenes), in a total of nine scenes grouped into three categories (not mentioned to the respondent), with three scenes in each category: order and visual stimulus - scenes with a clear organization of architectural elements and compatibility between neighbouring buildings, and with clear visual stimulus or focus of attention; order and low visual stimulus - scenes with a clear organization of architectural elements and compatibility between neighbouring buildings, but with low visual stimulus, what might allow the perception of monotony; and disorder - scenes without a clear organization, both between buildings and among the architectural elements of buildings, preventing the perception of order. Data from the questionnaires were analyzed by means of non-parametric statistical tests, such as cross-tabulations, Kendall W and Kruskal-Wallis. The main results show the potential of empirical aesthetics to explain aesthetic evaluations, and reveal the dominant and positive impact of the idea of order and visual stimuli in such evaluations. Nonetheless, regarding the examination of whether or not the differences between aesthetic evaluations of people with different levels and types of training, a greater aesthetic value was given to the idea of order and a greater aesthetic devaluation was given to the idea of disorder on the part of architects, compared to the group of non-architects college graduates and to the group of non-college graduates.