Tuol Sleng is nestled within in the heart of Phnom Penh, the capital of Cambodia. From the outside it looks unremarkable: a multi-story former high school with whitewashed walls and grey shutters. However, inside, Tuol Sleng holds a dark history.

Under the Khmer Rouge, Tuol Sleng was transformed from a school into Security prison 21 (S-21), a place in which some of the most violent atrocities of the Pol Pot’s regime were perpetrated. Originally named Chao Ponhea Yat High School, the complex includes five buildings in total. Several months after the Khemer Rouge took power in 1975, they implemented measures to convert the high school into a high-security facility. Between 1975 and 1979 it is estimated that over 15,000 people were imprisoned at Tuol Sleng. The prison held between 1,000 and 1,500 occupants along with a large security force.

Life within the prison was terrible, and the people imprisoned at Tuol Sleng were treated cruelly. Prisoners were shackled into their cells, forbidden to talk to one another and frequently beaten and tortured by the guards. All prisoners were interrogated during their stay at Tuol Sleng. These interrogations normally included torture: Prisoners were shocked with electricity, burned with irons and water-boarded.

In 2010, Cambodia convicted Kang Kek Iew, the chief of Tuol Sleng Prison, for crimes against humanity and grave breaches of the Geneva Convention. He was sentenced to life imprisonment, and died while still in custody in 2020.

Today, the former prison stands as a monument to the brutalities of the Khmer Rouge. It is now a museum dedicated to preserving the memory of those who passed through its gates. Several of the implements that were used to torture the prisoners are also on display along with a “skull map,” a map of Cambodia made entirely from human skulls and bones. Rooms that were once used to torture and abuse are now lined with thousands of photographs of those who were incarcerated there.