The ontological status of historic buildings has until recently been little explored, particularly in relation to their conservation. This is curious, for the assumed status and existence of buildings have critical impacts upon our attempts to conserve them. Conventional conservation thought has conceived buildings as solid objects constructed under the gaze of a single architect and retaining exemplar properties worth preserving. This paper offers an alternative and novel conceptualisation of buildings in time and space, drawing on the naturalistic ontology of Jubien and combining this with actor-network theory to explore how buildings might be conceived as multiple things with variant but persisting properties (some of which may be worthy of conservation). Using the moment of post-1945 reconstruction, we explore conservation of the architecture and spaces of Exeter (UK) to consider three objects, their nature, persistence, properties, and formation. Doing so reveals the multiplicity of material and social objects that may become entwined in attempts to conserve these buildings. Things such as ‘views’ become reconsidered as multiply constructed, with variant nonessential parts. The paper concludes that conservation practice requires a more heterogeneous understanding of these objects, how they are formed, and the potential for their social and material hybridity.