Museum collections contain large amounts of data and semantically rich, mutually interrelated metadata in heterogeneous databases. The publication of museum collections on the web is therefore a very promising application domain for semantic web techniques. We present a semantic web portal called "MuseumFinland -- Finnish Museums on the Semantic Web"1 [3] that contains some 4,000 cultural artifacts from the collections of three museums using three different database schemas and database systems. The system is based on seven RDF(S) ontologies consisting of some 10,000 classes and individuals. Categories and Subject Descriptors: H.3.6 Information Systems: Online Information Services General Terms: Design