CIDOC CRM is an ontology intended to facilitate the integration, mediation and interchange of heterogeneous cultural heritage information. The Semantic Web with its Linked Open Data cloud enables scholars and cultural institutions to publish their data in RDF, using CIDOC CRM as an interlingua that enables a semantically consistent re-interpretation of their data. Nowadays more and more projects have done the task of mapping legacy datasets to CIDOC CRM, and successful Extract-Transform-Load data-integration processes have been performed in this way. A next step is enabling people and applications to actually dynamically explore autonomous datasets using the semantic mediation offered by CIDOC CRM. This is the purpose of OpenArchaeo, a tool for querying archaeological datasets on the LOD cloud. We present its main features: the principles behind its user friendly query interface and its SPARQL Endpoint for programs, together with its overall architecture designed to be extendable and scalable, for handling transparent interconnections with evolving distributed sources while achieving good efficiency.