Cultural heritage collections are related to historical events and depict the customs of human societies. Their main characteristic is that they consist of heterogeneous objects, which usually are described by a variety of metadata schemas. Dublin Core Metadata Initiative plays a significant role in the interoperability of such collections. This paper proposes the exploitation of the CIDOC/CRM ontology as a mediating schema to which metadata sources can be mapped and integrated. In this context a methodology for mapping DC Types Vocabulary terms to CIDOC/CRM is presented, demonstrating a real-world effort for ontology-based metadata integration.