The Old Idaho Penitentiary State Historic Site was a functional prison from 1872 to 1973 in the western United States. The first building, also known as the Territorial Prison, was constructed in the Territory of Idaho in 1870. The territory was less than ten years old when the prison was built east of Boise. From its beginnings as a single cell house, the penitentiary grew to a complex of several distinctive buildings surrounded by a 17-foot-high sandstone wall.