The contribution under scrutiny here explores the design potential of heterotopic spaces, with particular reference to major historical buildings in the urban tissue—prisons, convents, asylums, Jesuit colleges—conceived not only as repositories of memory but also as spatial devices capable of generating new urban relationships. The essay draws on the Foucauldian notion of heterotopia to offer a theoretical and methodological reflection on the relationship between historical identity, functional marginality and reuse potential. It examines the operational implications of a restoration approach that addresses both the symbolic and material stratification of such complexes. The research is situated within an interdisciplinary framework that integrates architectural restoration, political and economic geography, sociology, and architectural and urban design, with the aim of establishing a shared lexicon and analytical tools for interpreting and transforming heterotopic spaces. The experimental phase of the project focuses on a sample of eight significant historical buildings located in the heart of Cagliari, exemplifying tensions between memory, neglect and underappreciation. A comparative reading with similar experiences in the French context—particularly in the city of Toulouse—enables critical reflection on policies for the reuse and valorisation of heterotopic heritage. Within this theoretical framework, the concept of restoration is not confined to mere conservation, but is instead envisaged as a strategic and operational instrument for guiding urban transformation processes, whilst ensuring the preservation of the semantic and historical intricacies of these sites. The study proposes a design paradigm that combines historical awareness with contemporary needs, outlining methodologies and operational criteria aimed at reactivating disused or underutilised spaces and reintegrating them into the fabric of contemporary urban and social life.