The Old Idaho Penitentiary is an old, historic prison located in Boise, Idaho. It opened in 1872 as a single-cell building and grew over time. It was built in the Romanesque style. It house over 13,000 inmates during its century-long lifespan. Two notable inmates were Harry Orchard, who assassinated Idaho governor Frank Stueneberg in 1905, and Lyda Southard, who killed her husbands to obtain their life insurance money. Today, the penitentiary is managed by the Idaho State Historical Society and is open to the public for tours year round.
Several buildings were built at the penitentiary, including a separate building for women inmates surrounded by its own wall, an administration building, a dining hall, and cell houses. The penitentiary also had a chapel and a recreational area for the inmates. The prison had a baseball team that played other teams in the area. In 1971 and 1973, inmates rioted protesting the prison conditions. In the early 1990s, the Idaho State Historical Society recorded interviews of prison guards for an oral history project; they can be accessed at the Idaho State Archives for research. The prison was listed on the National Register of Historic Places in 1974.