The aim of this work is to present a complex, web-based virtual museum application, integrating several tools for flexible management of heterogeneous and highly structured knowledge. All the used tools are compliant to W3C's standards. In particular, the complex network of associations and relations among concepts and objects (as typically found in a virtual museum environment) has been faithfully represented adopting W3C's Semantic Web standards. The proposed ontology allows for constraining, expressing and analyzing the intended meaning of the shared vocabulary of concepts and relations in the project domain of knowledge. As a valuable byproduct, this allows the virtual museum's visitor to interact by means of highly expressive queries.