The Preston School of Industry, also known as Preston Castle, was a reform school located in Ione, California, in Amador County. It was proposed by, and ultimately named after, state senator . The cornerstone was laid in December 1890, and the institution was opened in June 1894 when seven wards (minors under the guardianship of the state, but not necessarily juvenile offenders), were transferred there from San Quentin State Prison. It is considered one of the oldest and best-known reform schools in the United States.