From Ephemeral to Permanent: Street Experiments and the Evolution of Historical Urban Landscapes

From the 2005 San Francisco experiments by Rebar to the post-pandemic urban responses, temporary interventions, known as Street Experiments, are a consolidated trend in tactical urbanism. Public spaces, streets and squares have become key places for testing innovative, accessible, and landscape-sensitive urban models, integrating social interaction, recreation, and commerce. These, generally characterised by a bottom-up and reversible approach, link spatial alterations to urgent contemporary issues such as quality of life, energy transition, and active mobility. The study proposed here is part of broader research on street experiments aimed to investigate their transitional potential and propose design methodologies to bridge the gap between ephemeral trials and permanent urban improvements. In particular, this contribution proposes a reflection about how street experiments can act as a bridge to lasting structural changes in complex historical contexts. This study views the historic city as a place of long-term change where temporary experiments act as catalysts for permanent transformation. These approaches in stratified urban contexts, examining both the underlying processes and the physical alteration of urban fabrics, have been analysed. Through a selection of European case studies and international best practices, the study proposes a critical reflection on urban design within historical settings.