<p>Port Said, a strategic Mediterranean port at the northern entrance of the Suez Canal, possesses a layered urban fabric shaped by canal-era planning, colonial-era architecture, and nationalist interventions. Yet despite its rich historical morphology, the city is almost entirely absent from Egypt’s formal heritage registers and planning frameworks. This paper investigates how legal, institutional, and spatial dynamics have collectively undermined the protection and continuity of Port Said’s urban heritage. It combines doctrinal analysis of Egypt’s key heritage legislations with spatial-morphological mapping of two historical quarters and introduces a customized Heritage-Based Development Indicators (HBDIs) framework to quantify continuity, resilience, and vulnerability at the parcel level. Findings reveal that Port Said suffers from what may be termed “typological invisibility”—a condition where hybrid, vernacular, and non-monumental forms of heritage fall outside the narrow scope of existing laws. These legal blind spots are compounded by centralized governance, weak municipal capacity, and the absence of conservation-sensitive zoning mechanisms. Morphological analysis further shows a fragmented urban fabric, with declining typological continuity and increasing parcel-level risks in areas of high historical value. The paper concludes with actionable recommendations for expanding legal definitions, decentralizing heritage inventories, piloting conservation zoning, and establishing local heritage governance units. Port Said is proposed as a replicable model for second-tier heritage cities facing similar pressures in the Global South. The study contributes to global heritage discourse by bridging formal legal critique with spatial diagnostics and offering a scalable approach to embedded, development-oriented urban heritage policy.</p>