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.

A prison with guards on the outside but not on the inside because they fear for their lives. On the inside, the prisoners are in control: murderers, violent offenders, drug bosses. This is the prison city of San Pedro in La Paz, Bolivia, where the inmates rule and anarchy prevails. Money, violence and power. Only the strongest survive this lawless place, and they rule over the weak, demand protection money, rent for sleeping areas and determine what rights and obligations the prisoners have.

The Dallas County Jail in Texas - a mega-jail with room for 7,100 inmates, where everyone from small-time criminals to serial killers wait for their day in court. Mass processing of new inmates occurs on a daily basis: Up to 300 new arrivals per day are registered by prison staff. Those who enter must be aware of the turf wars. Gang warfare and turf battles are even more critical on the inside where there is less real estate to divide up. Gang warfare is even more relentless within these prison walls.

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.

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.