Mount Graham International Observatory (MGIO) is a division of Steward Observatory, the research arm for the Department of Astronomy at the University of Arizona. MGIO is at a height of 3,260 meters on Mount Graham near Safford, Arizona, 125 km northeast of Tucson. Two telescopes are in operation: the Vatican Observatory/Arizona 1.8-meter Lennon telescope (VATT) and the 10-meter diameter Heinrich Hertz Submillimeter Telescope (SMT), a joint project of Arizona and the Max-Planck-Institut für Radioastronomie, Germany. The Large Binocular Telescope, one of the biggest in the world, is under construction.