The Tuol Sleng Genocide Museum is a museum in Phnom Penh, the capital of Cambodia. The site is a former high school which was used as the notorious Security Prison 21 (S-21) by the Khmer Rouge regime from its rise to power in 1975 to its fall in 1979. Tuol Sleng in Khmer; means "Hill of the Poisonous Trees" or "Strychnine Hill".
Formerly the Chao Ponhea Yat High School 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 Formerly the Chao Ponhea Yat High School, 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.
In 1979, the prison was uncovered by the invading Vietnamese army. In 1980, the prison was reopened by the government of the People's Republic of Kampuchea as a historical museum memorializing the actions of the Khmer Rouge regime.
The museum is open to the public, and receives an average of 500 visitors every day.
The 114 photographs on this site are from Pol Pot's secret prison, codenamed "S-21" during his genocidal rule (1975-79). Between 1-2 million Cambodians--and many thousands of foreigners--were starved to death, tortured, or killed, during this reign of terror.
When the Vietnamese Army invaded in 1979 the S-21 prison staff fled, leaving thousands of written and photographic records. Altogether more than 6,000 photographs were left; the majority, however, have been lost or destroyed.

of the photographs that were printed for the book Killing Fields (Twin Palms Press) and for a traveling exhibition, which was on display at the Museum of Modern Art (NYC),
as well as many other locations.
Currently the Tuol Sleng Museum of Genocide, which is located within the former prison grounds, has the original negatives and a catalog of all 6,000 remaining negatives. Cornell University also has one of the catalogs, and the DCCam Project has also incorporated scanned versions of the images into their database, as well as Yale University.
In 1997 an American photographer/researcher identified and located the prison photographer, Nhem Ein, who had been living in a Khmer Rouge stronghold since 1979. Since meeting Nhem Ein, many other former prison staff have been identified and interviewed, adding to our knowledge of this piece of awful history.