Surveying a historic building means to measure, to detect and to analyse its geometries, its structural elements, the connections still existing between the different parts, in order to define its state of conservation, to make structural analysis and finally to plan a proper project of conservation, consolidation and reuse. The survey represents the first necessary moment for building's knowledge investigation. Nowadays, the wide use of tools and accurate surveying techniques makes it possible

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... to achieve an adequate level of accuracy of information related to the buildings; BIM tools offer a great potential, in terms of both planning and evaluation of the entire knowledge and conservation process of an historical building, and in terms of its management and future maintenance. In particular, the BIM technologies allow the communication between data coming from different software, allowing a greater exchange of information between many actors. In recent years, the generative process of Building Information Modelling (BIM) oriented to the digitization of built heritage has been supported by the development of new commands modelling able to integrate the output data produced by laser scanner surveys (point clouds) in major modelling applications. Structural elements, such as vaulted historical systems, arches, decorations, architectural ornaments and wall partitions with variable cross sections, require higher levels of detail (LOD) and information (LOI) compared to the digitalization process of new buildings. Therefore, the structure of a BIM model aimed at representing existing and historical artefacts (HBIM) requires the definition of a new digital process capable of converting traditional techniques used for the management of new buildings to those suitable for creation of digital versions of historical buildings that are unique of their kind. The aim of this paper is to present the results of the ongoing researches and activities carried out on survey and HBIM model of historical buildings.