The "Castle," built in 1890-1894, is the most significant example of Romanesque Revival architecture in the Mother Lode. It was built to house the Preston School of Industry, established by the State Legislature as a progressive action toward rehabilitating, rather than simply imprisoning, juvenile offenders. Doors of the 120 room "Castle" closed in 1960 after new facilities were completed.

California Registered Historical Landmark No. 867

Plaque placed by the State Department of Parks and Recreation in cooperation with the Amador County Historical Society, July 14, 1974.