Inside the World's Toughest Prisons

Greenland's Nuuk maximum security prison houses extremely dangerous prisoners, many of whom grew up alongside the guards now watching over them.

Once again, Raphael Rowe volunteers to go behind bars, this time in the Philippines at Manila City Jail, one of the world's most overcrowded prisons.

At Brandvlei Correctional Centre in South Africa, nearly all the convicts belong to dangerous gangs known for lethal stabbings.

An unnerved Rowe contends with aggressive cellmates at Maseru prison, where a high number of inmates are behind bars for rape.

The tropical island of Mauritius is home to Melrose maximum security prison, where even the smallest infraction is met with extreme punishment.

Schwalmstadt, a 12th-century fortress surrounded by a moat, houses some of Germany's worst offenders, many of whom attend intense therapy sessions.

Raphael Rowe spends a week behind bars at Tacumbu prison in Paraguay, where inmates scrounge in the trash in order to pay their own way.

Many prisons aim to punish and demean inmates. Norway's Halden Prison -- as Raphael Rowe is about to see for himself -- does things differently.

Raphael Rowe spends a week at a maximum security prison in Craiova, Romania, where the inmates include rapists, murderers and contract killers.

While spending a week inside Bogotá's fortress-like prison, Raphael Rowe must negotiate the oppressive atmosphere and deal with an ominous threat.

Though he's no stranger to life behind bars, Raphael Rowe concedes that Costa Rica's La Reforma Prison is certainly among the most intimidating.

In Belize Central Prison, the inmates are told that rehabilitation comes through God. Raphael Rowe investigates if this evangelical approach works.

Raphael Rowe visits the short-staffed Bomana Prison in Papua New Guinea, where near-constant food shortages keep the facility on the brink of chaos.

Ukraine's Zhytomyr Prison is operated with a skeleton crew that allows prisoners to freely roam the grounds -- often with potentially dangerous weapons.

Investigative journalist Raphael Rowe spends a few days -- both as a guard and a prisoner -- inside Brazil's gang-filled Porto Velho Penitentiary.

Connolly spends time in two different prisons in the Philippines, where overcrowding, gangs and severe intimidation are a way of life.

Mexico's el Hongo prison is home to murderers, hitmen, drug bossess and -- for one week -- Paul Connolly, who experiences life among the inmates.

Connolly serves time in Poland's Piotrkow prison, a maximun security lockup where the country's most hardened criminals stay in cells 23 hours a day.

Paul Connolly heads to Honduras, the murder capital of the world, to spend a week living as a prisoner inside one of the most dangerous prisons - Danli Prison.