## 1 Introduction  
Within the AEC (architecture, engineering, construction) industry, the BIM (Building Information Modeling) approach represents an increasingly widespread as much as necessary methodology. Being an interactive data archive [1, 2], these models contain geometric data but also non-graphic information, such as materials, thermal characteristics, costs and maintenance instructions, thus they consist in the creation of a central informative and shared model, integrated among every project participant, and it is configured as a dynamic system particularly helpful for the building's facility management (FM). On the other hand, the use of a GIS (Geographic Information System) is well stated in the literature for its usefulness when managing territorial and urban data, with a variety of different purposes and professional figures involved. The integration between these two domains and the complementary nature of the information provided by each technology could, therefore, lead to have a new data flow and a highly detailed and holistic picture of a project.  
Moreover, the latest technological developments, especially in the field of surveying and geomatics, encouraged the large acquisition of point clouds, thus speeding up the Scan-to-BIM process and contributing to the application of the BIM methodology also to the cultural heritage (CH) field. In this regard, the tendency to realize digital 3D models of CH, where historical data are associated to complex geometries, is growing. The aim is to support the conservation and management of built heritage, using the HBIM (Historic Building Information Modeling) approach, that mainly consists of mapping BIM objects over the dense point cloud and then configure the model as a digital data archive, collecting several existing kinds of documentation (historical, archival, iconographical and graphical), often fragmented, sectoral and not updated.  
In some specific cases, however, it is necessary to broaden the analysis scale, also including territorial data relating to the context in which the asset is inserted. This solution is particularly useful in the case of historical buildings subject to particularly vulnerable conditions or specific risks such as seismic risk. With respect to this matter, the integration of HBIM models in the GIS environment allows analysis to be carried out at different levels of detail (LoD), starting from the urban scale up to the architectural one, according to the objective and needs.  
In this framework, a multiscale project in which the different domains of BIM and GIS are integrated has been set up to ensure complete documentation of an architectural asset damaged by an earthquake. This research proposes therefore to analyze HBIM-GIS interoperability following two different integration methods: the first one relies on the use of commercial software with proprietary format, while the second one takes advantage of the IFC (Industry Foundation Classes) and CityGML (Geography Markup Language) standard formats, compliant with open source software. In detail, a focus on technical and semantic interoperability levels is carried out, investigating the loss of geometric and informative data, in addition to evaluate the results coming from the conversion of the HBIM model into a LoD 3 CityGML.