This paper presents AIR - a platform for building intelligent systems. Current IS platforms either are narrowly specialized (ontologies, expert system shells, etc.) or have complex extension mechanisms (i.e. do not use benefits of Model Driven Development). Based on OMG’sModel Driven Architecture and its standards, AIR core consists of various MOF-based metamodels. Presented metamodels are mainly intended, but not limited, to support emerging standards related to the Semantic Web. Basing its architecture on MDA, AIR can support metamodels of almost any domain, including non-AI related. AIR also includes an integrated development environment for building such systems, which is based on Eclipse. Presented platform is intended to be an integration point of various intelligent systems and mainstream software technologies.