The starting point of this research is the urban model promoted by the United Nations through the Sustainable Development Goals (SDGs). The importance of public spaces is especially highlighted in Goal 11.7: “provide universal access to safe, inclusive, and accessible, green, and public spaces.” The quality of public spaces can be properly assessed by reconsidering the quality indicators and investigating their development potential, which is the main focus of our research. This study is based on a theoretical and methodological reflection on the quality of public space, considering the contributions of some contemporary urban traditions and a few recent experiences. From this perspective, a variety of public space projects developed in the European sphere have been selected and analyzed. The quality parameters identified in this initial analysis were then applied to the analysis of nine representative case studies in three Spanish cities (Madrid, Barcelona, and Zaragoza). The main goal is to propose a methodology that helps to evaluate the quality of those public spaces and determine its relationship with the safety, accessibility, and inclusiveness conditions they offer.