In the framework of seismic risk assessment at the regional scale, the evaluation of the vulnerability of existing buildings is crucial and is generally based on the identification of structural typologies or archetypes, depending on the specific features of the constructions. With reference to residential buildings, which represent the majority of the building stock in urban environments, it is important to collect reliable data for a correct determination of masonry and reinforced concrete building types. In Italy, ISTAT (Istituto Nazionale di Statistica) provides a wide range of datasets that are generally used as the major data source for seismic risk studies. These data, generally available as aggregate data at the census zone level, cover the entire Italian territory, providing information about the characteristics of the buildings - such as construction age, materials, number of floors, and occupancy – and allowing the study of the vulnerability of these zones. The objective of this study is to evaluate their reliability through a comparison with building-by-building data. First, an on-site building-by-building investigation was conducted in a district of the city of Bologna. The collected data were then entered into a GIS using the census zones provided by ISTAT, creating a map with one layer displaying the data from the site investigation and another layer with the ISTAT data. In this study, observed building characteristics were compared with the corresponding ISTAT data to identify divergence and assess data accuracy on the census zone. Based on these data, masonry and reinforced concrete building typologies were identified and compared between the data sources. This comparison allowed to highlight, on the one hand, the importance of the survey activity, but, on the other hand, the potential use of the census data, already available for the Italian territory. In addition, with the objective of implementing the CARTIS methodology in the city of Bologna, both the data and the typological identification were adopted. The CARTIS form enables vulnerability analysis by contributing valuable data to improve the inventory of typological-structural distributions. In the CARTIS assessment, the study of the historical evolution of the city was fundamental for the creation of sectors, and various building features within the sectors - such as construction material, age, and building composition - are also taken into account. The research contributes to assessing the reliability of the ISTAT data for further vulnerability assessments of residential building assets.