Sofia Central Prison - a Bulgarian detention center, crumbling foundations and fit for demolition - derelict conditions too much to ask of anyone - even a criminal. Multi-prisoner cells, bunks stacked three stories high as well as a large count of isolation cells where prisoners spend 23 hours a day behind rusty bars, with nothing to do, vegetating their days away. Although the European Union requires 43 square feet space per inmate, prisoners in Sofia Central Prison have on average less than half. Central heating and hot running water are considered a luxury. This jail is a place of violence - inter-prisoner violence is rampant and many reports have emerged describing regular abuse by the prison guards.

New Bilibid Prison is one of the most notorious prisons in the Philippines. Originally designed to hold 1500 offenders, there are currently more than 8000 incarcerated there.

The Miami-Dade County Jail and the Miami Dade Boot Camp - the two toughest divisions of the Miami Dade prison complex but they couldn't be more different. Boot camp doesn't give its participants a minute to themselves, the inmates in prison have nothing but time to themselves. Two extremes, united in one world. One, a protocol to break the inmates by bootcamp drill, the other, old dilapidated group cells with its own special hierarchy within prison walls. Behind rusty iron bars, murderers, rapists and robbers adhere to their own rules to survive.

Tent City Jail - a prison in the desert of Arizona, USA. If you're in this place, you are in for tough times. As the name indicates, tents instead of cells make up prison housing, old army tents left over from the Korean War. The problem with tents - no insulation so it gets unbearably hot in the summer, freezing cold in the winter. Summer daytime temps can get up to 140 degrees Fahrenheit with nighttime temps often dropping to below freezing.

The pre-trial prison Urso Branco is one of the worst jails in all of Brazil. Riots have been taking place here almost every year since 2002. Gangs battling for control of the drug business are also fighting it out behind bars. They use every opportunity to eliminate rival gang members. In the past 20 years, more than 100 people have died in riots behind the walls of Urso Branco. A sad record for Brazil.

Colony Eight – one of the toughest and most notorious prisons in Ukraine. It is said that no one has ever managed to escape from here! Over eight hundred prisoners are behind bars in Colony 8 under maximum security. Until twenty years ago, the guards even carried out death sentences at this prison. Not any more – the concept is now a different one. Plenty of “freedom” on the one hand, draconian punishment and military drill on the other. Combined with permanent supervision: Around seventy cameras in the buildings ensure that anything moving gets noticed. One section of the prison is particularly notorious – the wing for the one hundred and sixty lifers: If you end up in this wing, you have absolutely nothing to lose. Because in Ukraine, life imprisonment means: literally being behind bars until you die. Access to this wing is specially secured. To gain entry, the guards must go through a multi-level security system of mechanical and electronic locks. Escape: impossible.

Maafushi Central Prison is a high-security prison covering an area the size of ten football pitches. Surrounded by six-meter-high walls, and the sea, the facility houses up to 800 criminals under the strictest security measures. All-round sureillance by a myriad of cameras, strict rules and daily searches are the key components in the success of this prison in the middle of a vacation paradise. The prison comprises a total of nine different units: The largest of these – Unit 9 - a star-shaped building, houses prisoners with higher security level. Units 5 through 8, which surround it, are for inmates with lower security level – and those soon to be released. The women’s wing is located at the other side of the prison.A workshop area is also available, where inmates with good behavior may be allowed to work.

The toughest and most heavily-guarded prison in Croatia. The country’s 500 most dangerous criminals serve their sentences here – and every day the struggle for survival begins anew.