Performance centres, once central to civic life, are increasingly perceived as formal and inward-looking institutions with limited relevance in contemporary society. Their monumental architectures often confine public engagement to enclosed interiors, leaving thresholds and transitional spaces underutilised and weakening the relationship between building and city. This research repositions architectural thresholds as active civic spaces that extend cultural life into the public realm. Using Milan’s Teatro alla Scala as a case study, the project explores how performance architecture can support continuous civic engagement by bridging public and private, formality and spontaneity, audience and passerby.