Arguably the penetration of Building Information Modeling software in the building industry is enabled by well-structured ontologies such as the Industry Foundation Classes (IFC) or green building XML. Acknowledging this, the UDIGISH WG aims to explore and assess possible specifications and data schemas which would facilitate interdisciplinary research for the study and reuse of built heritage in our cities, analysing and representing scales larger than the one of the building it self, like those of the building block, the street, or even of the neighbourhood. We argue, this multiscale data-driven study will facilitate a more holistic, integrated application of digital methods, such as BIM, modelling & simulation to cities, and will better contextualise cross-disciplinary enquiries. This we envision to bring us a step closer to big data for historic cities. Towards this goal, this presentation attempts to introduce some of the complexities of moving from the scale of the building data and its attributes, including heritage linked data, to the scale of the historic neighbourhood or cluster of buildings.