The historic center of Naples, recognized and protected as a UNESCO World Heritage site, faces pressing climatical and social challenges, including urban heat islands, desertification processes, tourism challenges and a lack of public space. Beneath its vibrant streets lies a network of underground tuff stone excavations that evolved from building the city above with its underground material. Its forgotten subterranean water landscape of aquifers, aqueducts, cisterns and channels serves as a continuous structure within the layeredness of the subterranean world and bares untapped potential for urban resilience and landscape-based urban development. This system was dug out by hand and therefore consists of human-scale underground spaces. This setting provides conditions that lead to the potential of redefining the understanding of public space in Naples: It is about connecting the surface with the underground public spaces through the water system. As the water still flows beneath the city, this thesis explores how these underground water structures can reactivate the system it runs through as well as the city’s surface public spaces, as a landscape infrastructure that creates better conditions alongside its reach. By connecting subterranean public spaces, aqueducts and cisterns through landscape-based design interventions to surface-level public spaces, the project envisions a socio-ecologically inclusive and climate-adaptive public space network that mitigates the city’s vulnerabilities while fostering creating identity and a common sense of belonging to the former water city Naples. The research maps the existing subterranean infrastructure and its spatial and functional relationships to the public spaces above it. Case studies, fieldwork and photogrammetry data inform strategies for transforming Naples from a two-dimensional into a three-dimensional heritage and climate-adaptive city. The project includes design explorations at multiple scales, combining architectural, ecological, and cultural elements to create surface- and subsurfacelevel public spaces that cool the city and people, enhance social interaction, a sense of belonging, and celebrate Naples’ water heritage again. This work contributes to the discourse on how heritage cities can adapt to future challenges by utilizing landscape-based urbanism approaches that prioritize the vertical logic of the landscape, resilience, inclusivity, and sustainability.