Studierstube is an experimental user interface system,which uses collaborative augmented reality to incorporate true 3D interaction into a productivity environment. This concept is extended to bridge multiple user interface dimensions by including multiple users, multiple host platforms, multiple display types, multiple concurrent applications, and a multi-context (i. e., 3D document) interface into a heterogeneous distributed environment. With this architecture, we can explore the user interface design space between pure augmented reality and the popular ubiquitous computing paradigm. We report on our design philosophy centered around the notion of contexts and locales, as well as the underlying software and hardware architecture. Contexts encapsulate a live application together with 3D (visual) and other data, while locales are used to organize geometric reference systems. By separating geometric relationships (locales) from semantic relationships (contexts), we achieve a great amount of flexibility in the configuration of displays. To illustrate our claims, we present several applications including a cinematographic design tool which showcases many features of our system.