Abstract. Current Web applications provide their information and functionalities to human users only. To make Web applications also accessible for machines, the Semantic Web proposes an extension of the current Web, that describes the semantics of the content and the services explicitly with machine-processable meta-data. In this paper we introduce an architecture of a Semantic Portal that provides a unique front-end to the information and functionalities of individual Semantic Web applications. To realize the portal we use WEESA to semantically annotate Web applications and provide the annotations in a knowledge base (KB) for download and querying. Based on that, the Semantic Harvester collects the KBs from individual Semantic Web applications to build the global KB of the Semantic Portal. Finally, we use Semantic Web services to make the portal a unique interface to the services of the Web applications.