Business decisions must rely not only on company-internal data but also on external data from competitors or relevant events. This information can be obtained from the WWW but must be integrated with the data in a company’s data warehouse. In this paper we discuss a system architecture for warehousing Web content for OLAP and DSS. A self-describing object model is used to make the implicit modeling and context assumptions explicit, both for the data obtained from the Web and the data already in the data warehouse. A domain-specific ontology provides a common interpretation basis for data and metadata. We propose an object-relational mapping that takes into consideration the peculiarities of relational data warehouses based on a star schema and propose a mapping rule language to describe the necessary transformation rules. The system framework described in this paper has been implemented in Java.