The digitization of the Gregorian Urban Cadastre of Rome (Catasto Gregoriano Urbano di
Roma) has started about ten years ago thanks to the funding by the Cariplo Foundation, and it
is now in its final stage. The project has been implemented by the Department of Urban Studies
of the “Roma Tre” University, the Archivio di Stato di Roma, the Sovrintendenza Capitolina and
the Archivio Capitolino. The research has allowed to reconstruct the archaeological and urban
image of Rome in the pre- and post-unification periods. The maps and registers of the
Gregorian Cadastre represent the basis of the Geographic Information System (GIS), which has
been linked to maps and documents from other sources: the 1748 map of Rome by G. B. Nolli,
a substantial number of datasheets from archive documents related to buildings and archeology, other iconographic documents concerning the architecture of the old town. The
project has a dual purpose: on the one hand, the implementation of a GIS able to store, manage
and disseminate data about the historic city from different sources; on the other, the activation
of a participatory and educational web tool open to a wide audience, not only to researchers
and scholars of this particular field. The web platform and the geographic database have been
fully implemented with Open Source products and software.