This research investigates the publicness of contemporary Mediterranean waterfronts through the pedestrian redevelopment of Via Roma in Cagliari, understood as a threshold between the historic city, the mobility system, and the port edge. Its aim is to understand how far a waterfront project can produce public urban space beyond pedestrianisation, visual openness, and formal renewal, and under which spatial, institutional, material, and everyday conditions that publicness becomes effective, mediated, or fragile. The thesis develops this question through a progressive structure: it first frames publicness as a critical urban problem, then interprets Via Roma as the primary case study, situates its spatial mechanisms within a controlled Mediterranean field of reference, and finally translates the findings into a design-oriented critical revision.