Exterior of the Tuol Sleng Genocide Museum

Formerly the Chao Ponhea Yat High Schoo], named after a Royal ancestor of King Norodom Sihanouk, the five buildings of the complex were converted in August 1975, four months after the Khmer Rouge won the civil war, into a prison and interrogation center. The Khmer Rouge renamed the complex "Security Prison 21" (S-21) and construction began to adapt the prison to the inmates: the buildings were enclosed in electrified barbed wire, the classrooms converted into tiny prison and torture chambers, and all windows were covered with iron bars and barbed wire to prevent escapes.