This paper explores the potential of traditional urban spaces in historic centers for the sustainable development of dense urban areas. Such spaces are supposed to be flexible with successive generations because they can facilitate different social, commercial, and religious activities throughout time. Thus, the main square of a Palestinian city - Nablus old city- was chosen for the study as the most important public space in the historic center. The paper summarizes the main manifestation of flexibility in the square that successfully assists in building a flexible place to satisfy users’ needs: rectangular shape, well enclosure, a ring of circulation, and extendible boundaries. the survey revealed that the young people group is the highest age group that has been satisfied with the daily activities of the square. Finally, three characteristics of activities are proposed to design a flexible public
space: diversity, fair distribution, and compatibility.