Riverbend Maximum Security Prison inmates tell their stories.

Inmates of California's Valley State Prison for Women try rehabilitation.

See how the once-infamous Rikers Island jail has reinvented itself.

Inside the largest maximum security facility in Salt Lake City. A "jail within a prison" protects some inmates from others.

Revealing of how these women deal with relationships and struggles.

Behind the walls of Kentucky's only maximum security prison.

Inside the maximum security facility in Eastern Iowa.

One of the most violent and volatile penitentiaries in the nation.

The Corcoran State Prison, located in an isolated valley, is one of California's largest maximum-security institutions.

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

Miami's prison system.

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Oklahoma inmates tell their own remarkable stories.

Half of Chicago's Stateville Correctional Center's inmates are imprisoned for murder.

LA County Jail is a system that is overcrowded, tough on gangs, and struggling with an increase in racial violence.

Inside the maximum security prison inmates call 'the end of the world.'

A profile of San Quentin State Prison in California; one of the most famous, most notorious penitentiaries in the world.

Inmates at San Quentin State Prison find ways to fight boredom.

Nine of the most violent criminals from the 'Lockup' series give chilling accounts of their crimes.

Inmates must develop methods to cope with the pressures and fear that come with incarceration.

Inmate violence including riots, shanks and attacks on officers.

Inmates' unwritten rules known as the Convict Code.

On a regular basis camera crew explore where even the most heinous violations are an every day activity.

Intimacy in prison.