Semantic technologies can be used not only to create ontologies as controlled vocabularies for historical architecture. Rather, they also make it possible to map the spatial and structural relationships within a building. Using an OWL ontology developed for the use in the MonArch system with a lean, non-event-oriented data model, the example of the Gothic church of St. Lorenz in Nuremberg shows how the relationships between the individual elements of a building (buildings parts, spatial units, structural components, architectural surfaces) have to be set. For this, a spatial breakdown of the building must be combined with a structural breakdown, with the architectural surfaces representing the interface between these two approaches. The result is a consistent structure graph and, derived from it, a basic rule for a semantic topology as an objectrelated data infrastructure that can also be applied to other buildings and enables the interaction of different disciplines in heritage conservation in everyday practice. Furthermore, the structure graph can be extended with additional specific information, such as the localisation of artistic furnishing or archaeological findings. At the same time, it is connectable to other data models, such as CRMba. The structurally detailed and networked storage of specialist information offers the possibility for a continuously updatable, Linked Data-capable recording of historic buildings, which can be used both as a building information system for the long-term preservation of a historic building and, in the case of indexing the historic building stock through the Semantic Web, would facilitate comparative research in architectural history, building archaeology, art history and restoration sciences.