This study presents a critical and multi-scalar analysis of the adaptive reuse and urban placemaking of an obsolete piece of Parisian railway infrastructure, Ligne de Vincennes (the viaduct section), framing it as a model of post-industrial transformation that integrates cultural vitality, environmental sustainability, and economic regeneration. Through a mixed-methods research design, combining in situ field observation, spatial and architectural analysis, and qualitative data synthesis, the project investigates how the Viaduc's rehabilitation contributes to evolving narratives of urban identity, heritage continuity, and place-based innovation. The Viaduc des Arts, a pioneering example of an inhabited viaduct paired with an elevated linear park, is examined as a paradigmatic case of infrastructural repurposing. The analysis yields ten transferable lessons clustered under six strategic themes: (1) structural and symbolic recovery of viaducts, (2) productive reuse of obsolete transport infrastructure, (3) microclimatic and environmental enhancement, (4) long-term economic return, (5) urban attractiveness and brand identity, and (6) local socio-cultural dynamism. Key enablers of success include the public acquisition and investment strategy, the architectural minimalism and contextual sensitivity of Patrick Berger’s design, and the governance model led by Semaest, which ensured the continuity of artisanal vocations within a managed cultural–commercial ecosystem. The project also supports sustainable development goals by conserving embodied energy, reducing demolition waste, and establishing circular economy synergies through the creative reuse of materials and space. By exploring the Viaduc as both a physical and symbolic urban artifact, the study advances a broader framework for post-industrial urban regeneration, highlighting the need to update methodological lenses and planning policies to better align with contemporary challenges in heritage reuse, ecological integration, and spatial equity. The findings serve as a transferable model for cities confronting similar dilemmas of obsolescence, identity, and resilience in the Anthropocene.