California Men's Colony, California

This correctional facility is located on the grounds of Camp San Luis Obispo, a National Guard training site. In recent years, the 356-acre complex houses around 4,200 inmates (with a design capacity of 3,800), in both  medium security facilities (level III), as well as minimum security (levels I and II) settings. At one time, this was the largest correctional institution - in number of inmates - in the country, until it was surpassed by a prison in Soledad (85 miles to the north), which itself was surpassed by a newer facility at Corcoran, in the Central Valley.  Camp San Luis Obispo has been a prison since 1954.