This paper introduces Portable Haptic Display (PHD), a novel platform-independent haptic rendering system that can be conveniently integrated into a large immersive virtual environment while maximizing the individual reusability of haptic interfaces and visual displays. The PHD has an architecture of distributed rendering where two computers (or clusters of computers) are in charge of all computations needed for rendering with corresponding displays and share necessary information via network. We report the architecture, implementation details, and performance evaluation results of the PHD in this paper. The PHD is especially useful in places that have multiple haptic interfaces and large immersive visual displays and that need to use them together as well as individually, such as research laboratories, companies, and hospitals.