This paper reports the current progress of the Venaria Reale pilot within the EU Horizon Europe project HERITALISE (2025–2028), using the Galleria Grande as a test case for a preventive-conservation Scan-to-BIM workflow towards digital twin integration. The workflow aims to deliver an HBIM base model that is geometrically reliable, semantically queryable, and traceable to its sources. Multi-sensor datasets, including terrestrial laser scanning (TLS), SLAM-based mobile mapping, and uncrewed aerial vehicle (UAV) photogrammetry, are georeferenced within a unified coordinate framework. Point-cloud processing uses a controlled UAV-TLS baseline as the primary modelling reference, with X70 SLAM data added only as local infill for verified gaps. Deliverables are organised through raw, working, and deliverable layers, supported by logged parameters, transformation matrices, and quality-control notes. Baseline quality is assessed through registration residuals, section-based inspection, and distance-based checks in critical indoor-outdoor junctions. Geometric modelling adopts a Revit-Rhino workflow guided by four decision factors: structural interpretability, semantic management needs, evidence strength, and modelling feasibility. Parametric, hybrid, and lightweight representations are combined according to object requirements and evidence limits. Dense sculptural and relief elements are reconstructed selectively through Rhino-based procedures and reintegrated into Revit as replaceable families, while complex vault surfaces and upper roof-truss layers are represented through differentiated LOG strategies. Semantic enrichment follows HERITALISE CDE/BEP governance. ObjectID anchors HBIM elements as information containers linked to an external SQL database. A first room/space crosswalk aligns 3,310 records across historical and current naming systems, supporting legacy linkage and interdisciplinary collaboration.