This article examines how intangible cultural heritage (ICH)—living knowledge, skills, and social practices —can contribute to sustainability-oriented historic preservation and urban regeneration by sustaining the territorial capital of places. The argument is developed through a qualitative, comparative case-study approach that synthesizes documentary sources (including National Park Service materials), published architectural and urban surveys, and prior scholarly accounts to trace how ICH is expressed in tangible form and mobilized in design and planning decisions. Two cases illustrate the claim across scales: a preservation–architecture design/build studio at Fort Pulaski National Monument (Georgia, USA), and the regeneration of Birmingham’s Jewellery Quarter (England, UK), where intangible industrial heritage and local industrial linkage support maker-based enterprises within a walkable historic fabric. Rather than presenting post-occupancy performance measurement, the analysis evaluates sustainability relevance through documented design strategies (e.g., climate-responsive vernacular precedents, material and craft logics) and district-level evidence of continuity in productive practices and social infrastructure. The paper concludes that sustainability frameworks in historic contexts are strengthened when cultural and environmental analyses are conducted in parallel, treating heritage not as a constraint but as an active resource for resilient, identity-supporting change.