It has become an increased challenge for designers to define the boundaries between the university and its surrounding city. The amount of space serving as a nexus between universities and urban areas is gradually increasing. This study defines such intermediate spaces as “the university-city interface”—areas that influence the university’s physical and functional connection to the surrounding city. The research presents comparative case studies of three universities in urban contexts—Harvard University, University of Pennsylvania, and Université Catholique de Louvain— by analyzing plazas and boulevards. These representative open spaces provide interfaces for both the university campuses and their surrounding cities. This paper analyzes design elements from the perspective of campus spatial structure, as well as locations and functions, to develop a comparative checklist for plazas and boulevards. The results offer a set of urban design principles for university plazas and boulevards that could significantly improve the quality of the university-city relationship. While these checklists and principles may vary depending on circumstances, they can be useful starting points for initializing design processes.