Alton, Illinois's State Penitentiary officially opened in 1833, making it the first state prison in Illinois. It was used to incarcerate convicted criminals from across the state and later served as a military prison. During the Civil War, the facility became the Alton Military Prison and was used to hold Confederate prisoners of war. More than 11,000 Confederate soldiers were held there before the prison closed.
Prison reform efforts led by Dorothea Dix focused on improving oversight and addressing concerns about harsh conditions and the management of inmate labor. Her criticism of the prison prompted reforms within Illinois's correctional system and contributed to the construction of a more humane prison in Joliet, Illinois, which opened in 1858.
Most of the prison was demolished in the early 1870s, with a pair of walls left standing as a memorial to Alton's contributions to the Civil War and the cause of social justice.