We have implemented a tabletop setup to explore augmented reality (AR) visualization. We call this setup an "augmented workspace". The user sits at the table and performs a manual task, guided by computer graphics overlaid on to his view. The setup serves as a testbed for developing the technology and for studying visual perception issues. The user wears a custom video see-through head mounted display (HMD). Two color video cameras attached to the HMD provide a stereo view of the scene, and a third video camera is added for tracking. The system runs at the full 30-Hz video frame rate with a latency of about 0.1 s, generating a stable augmentation with no apparent jitter visible in the composite images. Two SGI Visual Workstations provide the computing power for the system. In this paper, we describe the augmented workspace system in more detail and discuss several design issues.