Dorset Mountain, in southwestern Vermont on the Rutland-Bennington county line with its summit in Danby, is a Taconic Range peak surrounded by nearby summits and ridges and marked by a divide between watersheds flowing toward Lake Champlain, the Mettawee River, Batten Kill, the Hudson River, and New York Harbor. It is best known as the home of the Danby marble quarry, described as the world’s largest underground marble quarry, entered through the same opening for more than a century and extending about 1½ miles into the mountain. Since 1992, Vermont Quarries Corporation has operated the source of Danby marble. A proposed 1960s ski resort there was never built.