We propose an architecture for multi-user augmented reality with applications in visualization, presentation and education, which we call "Studierstube". Our system presents three-dimensional stereoscopic graphics simultaneously to group of users wearing light weight see-through head mounted displays. The displays do not affect natural communication and interaction, making working together very effective. Users see the same spatially aligned model, but can independently control their viewpoint and different layers of the data to be displayed. The setup serves computer supported cooperative work and enhances cooperation of visualization experts. This paper presents the client-server software architecture underlying this system and details that must be addressed to create a high-quality augmented reality setup.