The Piazza Municipio metro station in Naples, designed by Portuguese Pritzker Prize-winning architects Álvaro Siza and Eduardo Souto de Moura, provides an example of cross-cultural exchange between Portugal and Italy in contemporary architectural practice. Located in the core of the historic city centre, this large-scale project represented a deep infrastructural and urban regeneration intervention. During the excavations, multiple archaeological findings were discovered, representing information relevant to the history of Naples. Dealing with the preservation and integration of these elements into the new urban scenario added even more complexity to the construction process. By examining the station’s design choices, this paper seeks to outline how the architects’ method, rooted in the so-called School of Porto’s approach to intervention in historical contexts, shaped a new urban space where different heritage layers coexist and actively contribute to the contemporary city. The analysis will attempt to show how their collaboration with multiple stakeholders and experts—such as Soprintendenza’s archaeological officers as well as engineering and construction companies—led to a final project that fostered sustainable urban innovation. This analysis may contribute to the ongoing discourse on contemporary exchanges between Portuguese and Italian architectural cultures.