Behind Bars The Worlds Toughest Prisons

Colony 100 in Kharkiv, Ukraine, is a prison for hardened criminals. Inmates are either repeat offenders or have committed crimes so heinous, they'll never leave their 100-square-foot cell again.

The Philippines' South Cotabato Provincial Jail houses over 2,000 inmates when it was designed for 600. President Duterte's war on drugs overwhelms the system, putting the guilty and innocent behind bars together.

Inmates at Carcel Distrital in Bogota, Colombia, fight many battles: other prisoners, guards and themselves. A strict approach is necessary to keep prisoners in line, especially when nearly 1,000 of them aren't used to rules.

Prisoners at Carcel Distrital in Bogota, Colombia, may wait years for their final judgment because justice moves slowly in Colombia. This creates many frustrated people in one place, leading to everyday disputes, fights and riots.

El Hongo is Mexico's only incorruptible prison in a country plagued by corruption and violence. The prison is a high-tech fortress of sensors, cameras and phone jammers, and snipers make sure nothing gets in or out.

Armenia's Armavir Prison is controlled by a mysterious criminal brotherhood that oversees the drug trade and smuggling. However, the prison is the first attempt at limiting their influence by locking them in dedicated blocks.

La Mesa, a Mexican prison just over the US border, houses drug traffickers, rapists and cartel killers that hardly get to leave their cells. The facility is ruled with an iron fist so its infamous history can never be repeated.