BIM (Building Information Modeling) processes are the most effective way to know existing architectural structures, integrating the most advanced potentials of 3D modeling and the structured storage of heterogeneous information. Many HBIM (Heritage Building Information Modeling) applications lead to the systematization of survey data, even though a univocal working method is not yet clearly defined. This research considers the decomposition of architecture, based on structured criteria, and its reconstruction, through ideal models, as the main moments of the HBIM process. This hypothesis is verified through a procedure that links the survey 3D data with the characteristics of the ideal HBIM model, which allows a continuous comparison between the project model and as-built. The research provides for the setting up of a general methodology that, according to a growing approach to the complexity of the analyzed buildings, compares the process followed on two architectural structures. The study analyzes some important HBIM issues: The relationship between the semantic modeling and the surfaces’ continuity of architectural heritage; the relationship between the elements standardization, geometric irregularities, and material heterogeneity; the reliability of the built models; and the evaluation of the gap between an ideal model and the objective accuracy of surveying.

The first 25 years of the so-called ‘digital revolution’ have deeply changed the methods and tools of our interaction with the ‘architectural domain’. Traditional lines sketched on traditional paper have been soon replaced by digital mathematical entities created by Computer Aided Design (CAD) systems. Nowadays, we are witnessing a similar shift this time from CAD to the Building Information Modelling (BIM), a system that shows the ability to manage the fragmented but interconnected information needed in building workflow in an ‘all-in-one’ environment. However, while BIM is already a powerful option for new structures, for existing ones (especially when historical) it still reveals inadequate. This issue, seriously affecting the future of the built environment, cannot be ignored in order to control the ‘shaping’ of buildings and cities and especially when their design aims at becoming ‘regenerative’. In this framework, this chapter will try to outline the many difficulties connected with the application of BIM to the existing building stock: a problem that is generally regarded as ‘sectorial’ but that on the contrary will be crucial in view of a probable generalized adoption, considering that existing constructions represent about 70% of the whole European stock.

The paper aims at investigating modelling strategies in HBIM context to identify at what extent the final use of the model might affects, or should affect, the modelling approach itself. Moreover, the discussion wants to shed light on the possibility of connecting in just one digital environment several instances connected to the building. These aims will be discussed presenting and evaluating two different modelling approaches: the “black box” modelling and the “white box” model-ling. The two terms are partially borrowed from computer science to explain two types of testing. The “black box” testing is performed without any preliminary knowledge about the system functionality and internal components; on the contrary, the “white box” testing, implies a full knowledge of the system. These two approaches will be compared to two ways of conceiving a building information model. In conclusion, the paper will investigate the possibility to integrate in just one model, the grey box model, the two ones previously discussed.

BIM represents a significant step towards digitalization and innovation in the public construction sector in Italy, and as of 1 January 2025, its adoption became mandatory for all public work. Recognizing the importance of this shift, the Sapienza University of Rome developed a set of standards and guidelines between 2018 and 2024. These guidelines have now been officially adopted by the Buildings Maintenance Area of Sapienza for the application of BIM in service and work contracts. They are consolidated into a document known as the Sapienza Protocol, which serves as a reference for the creation of information-rich models of university heritage buildings, encompassing both existing structures and those to be constructed from scratch. The Sapienza Protocol outlines a modeling process that integrates surveying, geometric modeling, and an informational framework, combining theoretical principles with methodological approaches tested in the HBIM research domain. This approach ensures that both the technical and historical characteristics of buildings are appropriately represented. The purpose of this manuscript is to describe the evolution of the Sapienza Protocol, from its initial version to its current form. It highlights operational procedures and technical solutions, showcasing how the protocol has adapted to address the complex needs of managing and preserving architectural heritage in a digital context.

This paper presents a semantic classification workflow applied to the UNESCO World Heritage site of Aachen Cathedral, integrating 3D survey data and Machine Learning (ML) techniques. The research focuses on the Westwerk area and combines Terrestrial Laser Scanning (TLS) and photogrammetric point clouds for material and construction technique identification. A hybrid approach was adopted: 3D geometry-based classification using supervised algorithms (Random Forest) and 2D image segmentation via META’s Segment Anything Model (SAM). The 3D method proved suitable for distinguishing features with strong morphological differentiation, while the 2D approach was more effective for visually subtle or geometrically similar elements. Annotated 2D masks were projected onto the 3D model to improve classification reliability.The study demonstrates the potential of integrating spatial and radiometric data for scalable, semi-automatic classification of historic masonry. Results contribute to the development of enriched, semantically annotated 3D datasets supporting documentation, conservation planning, and future research on complex heritage sites.

The article illustrates the digital documentation workflow adopted to effectively use digital survey outcomes in supporting the knowledge and conservation of built heritage. This study was developed as part of the Project of Significant National Interest (PRIN), titled “KNOW.it Transition in Digital Age: KNOWing our background to refine our future”. The research focuses on the cities of Jaú and São Carlos, applying a rigorous methodology that combines archival research, photogrammetry, laser scanning, and 3D modelling. This approach is used to identify, analyse, and digitally reconstruct Italian-influenced eclectic architecture from the late 19th to early 20th century. The initiative supports both scholarly research and public dissemination through a digital platform that will host interactive maps, historical documents, 2D drawings and 3D models. By linking academic research with diasporic memory, KNOW.it highlights how digital tools can preserve and reactivate cultural legacies, fostering transnational heritage dialogue. The project’s use of social media further engages local communities in a participatory process, enriching its digital archive with crowdsourced memories and documents. The project opens up new possibilities for international cooperation, digital heritage practices, and the study of architectural migrations, showing how critically informed digital tools can recontextualise and enhance dispersed historical knowledge.