This paper illustrates the OntoWeaver modelling approach, which relies on a set of comprehensive site ontologies to model all aspects of dataintensive web sites and thus offers high level support for the design and development of data-intensive web sites. In particular, the OntoWeaver site ontologies comprise two components: a site view ontology and a presentation ontology. The site view ontology provides meta-models to allow for the composition of sophisticated site views, which allow end users to navigate and manipulate the underlying domain databases. The presentation ontology s the look and feel for site views and makes it possible for the visual ce and layout to be specified at a high level of abstraction.