OH_FET formalism has been designed to analyse urban fabric over long time spans (Lefebvre et al., 2008; Rodier and Saligny, 2010; Rodier et al., 2010). The conceptual model is founded on the idea of historical object (OH – objet historique) which is defined as the Cartesian product of three elementary dimensions: social use (what), space (where) and time (when). Processes are performed in Python programming language and data are stored in various kinds of spatial database. With a minimum of required data from archaeologists’ observations, the application allows users to automate the calculation of standardised indicators about urban transformations and to generate graphical and cartographic representations. As an example, it is possible to query the database about functional transformations over time and across space either quantitatively (How many social uses for a given date in a given place?) or qualitatively (What changes occurred in social uses over time for a particular place?).