We present HOMER, a CASE tool for building and maintaining complex, data-intensive Web sites. In HOMER the processes of creation and maintenance of a Web site are completely based on the adoption of suitable models, to describe the various aspects of the site (content navigation structure, presentation). The development of a site does not require any code writing activity: based on the results of the design process, the system automatically creates programs to implement the site, statically and/or dynamically, as needed; also, the system does not depend on any specific tool or language: it has a modular architecture, which integrates external servers for specific tasks; finally, the system sup- ports site administrators for several maintenance activities, which can involve changes over the site at different levels.