Context information produced by various interconnected sensors and software sources needs to be efficiently identified and located by a context-aware application. In this paper, we propose an inter-space context discovery platform, called Orion, which allows context to be discovered and retrieved from multiple smart spaces. Orion employs semantic overlay network peer-to-peer architecture to provide connectivity between the smart spaces, allowing lookup query to be forwarded to the destined spaces. On the other hand, to overcome data heterogeneity, Semantic Web ontology-driven approach is used for the context modeling and matchmaking.