Public open spaces improve the quality of life in cities and form places for community gatherings and outdoor activities. This study examines the preference of pedestrians for the design features of urban squares. Field surveys on the perception of environmental stimuli were conducted in five squares in Athens, Greece in three seasons (summer, autumn and winter), while a mobile station monitored environmental conditions at the moment of the interview. The questionnaire included an item on the preference for improvement of urban design features (i.e., vegetation, water elements, view, and sport spaces) at the monitoring sites. Overall, 1,858 pedestrians participated in the survey. Of these, 84.4% reported a preference for the monitoring site to be improved for urban design. More vegetation (60.7%) and adding water elements (28.9%) were the most popular suggestions. The preference for increasing vegetation was prevalent in all three seasons (summer, 63.8%; autumn, 61.5%; winter, 57.3%; p=0.05). The preference for water elements was more prevalent in summer (39.6%) than autumn (31.5%) and winter (17.3%; p<0.001). The results show that most participants would prefer the monitoring sites to be improved for urban design reporting vegetation as the main element for improvement.