The morphology of the urban edge. Traces of Bologna’s historic walls as an opportunity for public space design

The reading of urban form offers a key for interpreting the city as a stratified system in which historical permanences and contemporary transformations coexist. In Bologna, the 13th-century wall circuit defining the boundary of the historic centre represents a morphological and symbolic threshold between the ancient and the modern city. Although largely demolished, the walls persist through material fragments, urban alignments and open spaces that continue to structure the urban edge. This work proposes a systemic historical and morphological analysis of Bologna’s wall system and its surrounding areas, interpreting these traces as operative material for the project of public space. By investigating the relationships between residual archaeological elements, road axis, urban voids and green areas, the study explores the potential of the historic wall edge as a spatial infrastructure for urban regeneration. Interpreting the historic city as a dynamic palimpsest, the paper argues that the traces of Bologna’s walls can support strategies aimed at reconnecting fragmented urban areas, enhancing environmental continuity, and strengthening the relationship between cultural heritage and public space. In this perspective, urban morphology emerges as a critical lens for rethinking historic urban edges not as residual limits, but as active and adaptive components of the contemporary city.