Since 2005, the MPIA has been operating the Large Binocular Telescope (LBT) together with partners from Germany, Italy and the USA and equipping it with measuring instruments. The LBT is located on Mount Graham near Tucson, Arizona, which is 3190 m high. On its mount, it carries two primary mirrors, each 8.4 meters in diameter, making it the largest optical reflecting telescope with single monolithic primary mirrors in the world.