Lockup

California's Kern Valley State Prison opens its doors in 2005.

Behind the walls of the Iowa State Penitentiary in Fort Madison.

The Brushy Mountain facility has an unusual population of lifers and first-time inmates.

Alabama's Holman maximum security prison.

Originally built to house prisoners during the Civil War, the Indiana State Prison is now home to nearly 2,000 maximum security inmates.

Life inside Alaska's Spring Creek Correctional Center.