We built a system that allows a robot manipulator to be teleoperated via the WWW. Although the field of teleoperation dates back over 50 years, the WWW provides a low-cost and widely-available interface that can make teleoperated resources accessible to anyone with a desktop or laptop computer and modem. The "Mercury Project" consists of an industrial robot arm fitted with a CCD camera and a pneumatic system. We placed a sandbox filled with buried artifacts in the robot workspace. Using the ISMAP feature of HTTP, users can remotely move the camera to view desired locations or direct a short burst of compressed air into the sand to view the newly cleared region. To our knowledge, the Mercury Project is the first system to permit WWW users to remotely view and alter the real world. This paper focuses on interface design, robot hardware, and system architecture.