This paper develops an overall architecture for integrating CAD and virtual worlds. The advantages of having access to the building model in a virtual world include the collaborative nature of the world. The EDM database as an object-oriented database is developed to establish a common object-oriented representation of building model, which can be accessed by both CAD systems and virtual worlds. The integration between CAD systems and an EDM database is implemented through the use of Industry Foundation Classes (IFCs) as an intermediate data model and the communication between the database and virtual worlds is developed through agents.