San Quentin Rehabilitation Center (SQ), formerly known as San Quentin State Prison, is a California Department of Corrections and Rehabilitation state prison for men, located north of San Francisco in the unincorporated place of San Quentin in Marin County. Established in 1852, and opening in 1854, San Quentin is the oldest prison in California. The state's only death row for male inmates, the largest in the United States, was located at the prison. Its gas chamber has not been used since 1993, and its lethal injection chamber was last used in 2006.
https://en.wikipedia.org/wiki/San_Quentin_Rehabilitation_Center