Urban Transition and the Return of Neighbourhood Planning. Questioning the Proximity Syndrome and the 15-Minute City

European policies acknowledge cities’ major roles in building greener and just urban habitats. When rethinking cities’ spatial organisation, the call is for creating better liveability conditions at the level closest to citizens. In this frame, research into the impacts of COVID-19 has led to a revival of neighbourhood planning and the 15-Minute City has been proposed as a successful model for cities’ recoveries in the name of regained proximity to collective facilities. This article questions the long-lasting neighbourhood image that the 15-Minute City refers to, by exploring recent experiences that renewed its application. We begin with a literature review, and then develop an evidence-based approach to a deeper analysis of policy design and implementation focusing on the Italian city of Milano. Discussion and conclusions highlight critical issues and potentials of the 15-Minute City. If the threat is that of a simplified and rhetorical use of this idea, its ability to gather plural actions under an appealing flagship can be a powerful driver for urban regeneration policies. However, being more than just a reproducible spatial model, the 15-Minute City needs to be handled as a complex planning device, whose effective implementation depends on the specific characteristics of the urban environments it applies to and on the strong intertwining of different policy fields and tools.