In an increasingly crowded world, underground excavations are needed to provide facilities that cannot be located above ground. Henderson Mine would provide a world class facility for a state-of-the-art experimental underground excavation laboratory. It would provide unprecedented testing facilities for tunneling technology including instrumented tunnel construction and tunnel sealing experiments, modern (including unmanned) excavation technology and equipment development. Mechanical and engineering properties of rocks under varied stress conditions during excavation of large cavities can be studied using different modeling techniques, micro-seismic research and other emerging rock mechanics technologies. Such a facility would be invaluable to institutions, contractors, and manufacturers in mining and underground construction that do not have such a facility or need a larger one.