A recent study and the digitalization of historical centres have developed a completely new strategy for the conservation management of urban buildings through the ‘Risk Map’ of MiBAC. Issues, aims and structure of the Territory Information System (TIS) have been wholly outlined in a dedicated book that describes the structure of the system, also following a historical framing of the debate and the previous experiences. The elaboration of a dedicated ontology adds the opportunity to make the same data available to other kind of software, beginning from HBIM Systems. This aim is pursued developing a special extension of CIDOC-CRM, an already consolidated ontology initially dedicated to the conservation issue of museums. The work has firstly considered the field of architectural conservation and recently further developed addressing historical centres. In this way, a synthetic description of the buildings, including the main features together with vulnerability and transformation index, will allow, through the 3D representation of the town, a stable monitoring of the urban tissue, constantly up to date with the new data deriving from the interventions gradually realized.