This article proposes an innovative methodological framework to identify commercial practices and spaces in early modern cities, based on Portuguese sources from the 14th to the 16th centuries, in which the explicit designation of “market” is often absent. Drawing on the concept of the “invisible market”, the research moves away from the search for formal labels and focuses instead on identifying functional indicators of urban commerce through three interdependent levels: technical-architectural vocabulary porch (alpendre), arches (arcos), air (ar), tents (tendas) and shop (boticas), spatial organisation (location, connectivity, morphology), and regulation (charters, royal decrees, municipal statutes, lease contracts, council records). The method, systematised in tables and replicable, is structured in three stages: lexical survey, contextual reading, and spatial-normative cross-referencing. This approach supports the argument that urban commerce was
functionally and legally embedded in the urban fabric, even without being formally designated as a “market”. The article draws on an extensive documentary base, complemented by visual sources, and discusses the limitations, comparative potential, and applicability of the framework in Iberian and Ibero-American contexts. The proposed methodology thus offers a new way to trace commerce in the city and to understand its role in urban transformation, constituting an original contribution to the interpretation of city formation through its commercial spaces and architectures.