Within the ongoing scientific and disciplinary debate on the interplay between climate change and land-use governance, this paper highlights the critical role of urban planning and design in shaping environmental regeneration strategies for coastal urban areas vulnerable to flooding phenomena. These flood events—driven by the combined effects of sea-level rise (SLR) and riverine flood—represent one of the key challenges facing the “global risk society” given their increasing impact on urban areas and the tangible economic, social, and environmental damages they produce. In this context, this paper presents selected outcomes from the findings of the research project “Climate-proof planning and regeneration strategies for adaptation to sea-level rise. Experimentation and innovation in local urban planning in at-risk areas of the Lazio region”, conducted at Sapienza University of Rome. The project focuses on research and experimental planning in coastal areas of Lazio identified as being at risk of SLR-related flooding by 2100. It aims to define theoretical–methodological and operational references for urban regeneration with an ecosystemic approach within the framework of so-called climate-proof planning. This study examines three macro-areas, further subdivided into seven distinct sites, categorized by their prevailing urban functions. For each site, following a preliminary assessment of flood-prone zones, tailored design actions are proposed. These actions are framed within three overarching of urban resilience strategies, developed in previous research by the authors: “defence”, “adaptation”, and “relocation”.

The processes of metropolization, which have transformed cities into complex territorial systems characterized by increasing fragmentation and development beyond administrative boundaries, represent a key issue in the scientific and disciplinary debate on intermunicipal governance. These dynamics highlight the need to define criteria for delineating optimal cooperation areas, referred to as homogeneous zones, to enhance coordinated planning efforts. This contribution, framed within a doctoral research project conducted at the Department of Planning, Design, and Technology of Architecture (PDTA), Sapienza University of Rome, analyzes the theoretical and methodological framework for defining intermunicipal cooperation areas. It examines the criteria adopted at both national and European levels for their delineation, with a specific focus on the concept of homogeneous zones. The objective is to understand how intermunicipal planning can overcome the limitations imposed by administrative fragmentation through innovative models of territorial governance. To this end, the research presents a comparative analysis of two Italian case studies: the Emilia-Romagna and Tuscany Regions. Both have developed intermunicipal cooperation strategies but have adopted distinct approaches in defining homogeneous zones for planning purposes. The comparative analysis highlights the key role that these territorial areas play in intermunicipal planning, promoting a more integrated and strategic territorial management. By responding to local specificities and ongoing socio-economic transformations, homogeneous zones emerge as an essential tool for fostering effective and adaptive governance models.

Territorial transformations and increasing environmental pressures call for a rethinking of the scales and modes of spatial planning and governance. In Italy, Regions have assumed a central role in the top-down definition and management of territorial policies, particularly in identifying optimal territorial areas for the joint exercise of municipal functions, while Unions of Municipalities represent bottom-up forms of cooperation that often do not fully coincide with such delimitations. This paper proposes a comparative critical analysis of the Tuscany and Piedmont Regions, aimed at assessing the coherence between optimal territorial areas defined in regional normative and planning instruments and the Unions of Municipalities established. Through spatial and regulatory analysis, the study highlights asymmetries between administrative-institutional boundaries and territorial structures, underscoring the need to integrate morphological invariants and relational systems in defining intermunicipal cooperation areas.