In the rich and complex framework that today define the debate about urban commons, our contribution focuses on the relations between commoning processes and urban regeneration. In the last 5 years, we can see emerging different experimental public policies and urban transformation processes that aim not only to give citizens the possibility to manage public properties in a common interest, but also to encourage private groups to take charge of the architectural transformation of public buildings. This paper focuses on the extents and limits of the comparison between two European countries, Italy and France, more precisely between the cities of Turin, Bologna and Grenoble. In the three cities we find similar case studies in terms of actors, stakes and urban impacts. To enquire on those similarities needs a methodology that can highlight the way in which those apparently sporadic cases challenge the existing knowledge on urban commons. Our objective is to question not only the impacts of commons on city governance, but also on how spaces are reshaped and redesigned by commoning practices.