This paper draws on the development of a critical mapping methodology capable to acknowledge spaces for (potential) commons and commoning practices in the contemporary city. Mapping the commons in cities has been investigated by very few projects so far. Some projects provided maps which did not exist before, with under-used spaces in town (public and private as well): experiences with respect to which ‘Mapping the urban voids’ (2012) or ‘Ex vuoto Pavia’ (2016) can be considered interesting samples. In some cases these are also coupled with GIS referenced maps to better match available information such as past uses, and other relevant planning information. Most interestingly, few projects provided critical cartographies in which information on local groups and communities, activities and other informal evidence were collated. (De Soto, 2015). However, mapping urban voids or vacant places does not provide as such a map on commons or coming actions. Urban commons - considered as essentially composed by three sets or layers of elements such as commons pool resources, social groups and/or local communities, set of rules or governance – are to be interpreted (and mapped) not as a fix or invariable status, rather a dynamic condition which is evolving over time. Some authors, indeed, couple the name commons with the verb, commoning, to more clearly describe its being an action. In such circumstances, the aim of mapping places of current commons, or places suitable for commoning actions, calls for an new approach to the matter. The paper proposes a methodology, which include secondary data collection and primary data through fieldwork, at different scales of action (both architectural and urban). This is based on various methods and tactics including psycho-geographical tours, both non-interactive and interactive forms of observations, critical mapping of several features. The methodology has been preliminary tested on the University central buildings in Pavia, and consequently applied to the whole town. The mapping led to the identification of case studies, followed by a more in depth analysis, which aims at revealing spatial features in connection to uses and forms of appropriation. The process of critical mapping, together with the outcomes of on-site surveys and fieldwork, aims at showcasing both what is already taking place and potential or possibilities for future uses. The methodology - still in an experimental phase and tested only in academic field so far - can be considered a possible model for mapping and acknowledge space for potential commons, through the identification of a network of relationships, both tangible and intangible. Moreover, the consequent findings can provide a useful support for public administrations in driving participatory and community based projects on the basis of a more accurate match between special features and socio-economic drivers. A critical and dynamic mapping of several different layers – including uses, community and spaces - can become a tool for the development of bottom-up, economically viable and environmentally sustainable urban actions which focused on the reuse of places, their intrinsic relationship with local groups and stakeholders which can proactively contribute to the ‘making’ of these places in the form of co-production.