The discovery of iron ore near Chateaugay Lake in 1831 started the settlement later known as the town of Dannemora. In 1832, several local businessmen entered into partnership to mine the ore. St. John B.L. Skinner, a lawyer in Plattsburgh, owned most of the land and named it Dannemora. Dannemora's history is intertwined with iron ore and the development of the prison. The town is located in Clinton County in the foothills of Dannemora Mountain and is within the Blue Line, which marks the border of Adirondack Park. The prison is built on the side of the mountain, and a building to its right, which was the State Hospital for Insane Convicts, is now called the Annex. Surrounding Dannemora are Lyon Mountain, Chazy Lake, and Upper Chateaugay Lake.