Preston Castle in Ione, CA was officially known as the Preston School of Industry. That moniker is the name of a one of the oldest and best-known reform schools in the United States.

The institution was opened in June 1894 when seven wards (juvenile offenders), were transferred there from San Quentin. The original building, known colloquially as "Preston Castle" (or simply "The Castle"), is the most significant example of Romanesque Revival architecture in the Mother Lode. It was vacated in 1960, shortly after new buildings had been constructed to replace it.

Since 1960 the castle appearing building has been slowly disintegrating. From a distance it looks stately; closer it looks suspicious; inside, its falling apart and really creepy. Entropy lives at Preston Castle.