This article presents a selection of case studies developed within the Erasmus+ project CoVHer –Computer-based Visualization of Architectural Cultural Heritage (2022–2025), alongside the underpinning methodological framework. The project focused on the digital reconstruction of architectural works that have been lost or were never built, addressing critical concerns regarding the scientific credibility, transparency, and educational value of such hypothetical reconstructions. Building on previous collaborations, including contributions to the DFG Research Network: Digital 3D Reconstructions as Tools of Architectural Historical Research (2018–2022), CoVHer further developed key concepts and best practices in the field. It aimed to establish a shared methodology and vocabulary for virtual 3D reconstructions, especially in cases where physical remains are absent. The project produced four main results: (1) a set of theoretical principles and operational guidelines (CoVHer Guidelines) for assessing the scientific quality of 3D reconstructions, structured around criteria such as constructive accuracy, source traceability, interoperability, and communicative effectiveness; (2) a series of 3D case-study reconstructions developed by partner institutions and evaluated according to these criteria, incorporating polygonal and mathematical modelling as well as virtual and mixed reality technologies; (3) the CoVHer Repository, an online platform designed to store and share scientifically validated reconstructions, complete with documentation and metadata structured using a CIDOC Conceptual Reference Model (CRM)-based ontology; and (4) the development of Open Educational Resources, including a Massive Open Online Course (MOOC) hosted by the University of Bologna and blended learning modules implemented across participating institutions. Through this integrated approach, CoVHer has contributed to defining standards and tools for scholarly reconstruction practices, promoting critical engagement with digital heritage, and enhancing educational strategies in architecture and historical studies. The project’s outcomes are intended to support researchers, educators, and cultural institutions in producing and disseminating credible, transparent, and reusable virtual reconstructions.