Toul Sleng Genocide Museum – Phnom Penh
S-21 – The Cambodia’s Darkest Chapter
Located in Phnom Penh, the capital of Cambodia, the Tuol Sleng Genocide Museum is one of the country’s most somber and historically significant sites.
Once known as Security Prison 21 (S-21), this former school-turned-prison became one of the most notorious centers of interrogation, torture, and extermination during the Khmer Rouge regime between 1975 and 1979.
Today, it stands as a memorial to the victims and a stark reminder of the atrocities committed under Democratic Kampuchea.
From School to Prison
Originally a secondary school, the building was repurposed by the Khmer Rouge into a high-security detention center. Over 18,000 prisoners, including men, women, and children, many of them Khmer Rouge cadres accused of betrayal were imprisoned here.
Inside its walls, detainees endured harsh interrogations, inhumane torture, and brutal confinement. Most of them were eventually executed either within the prison itself or transferred to the nearby Choeung Ek Killing Fields for mass executions.
Preservation as a Museum
When the Khmer Rouge regime collapsed in 1979, Tuol Sleng was left largely intact. The new government preserved the site as a crime scene and historical archive. It was later transformed into a museum to honor the victims and ensure that the tragedies of the past are neither forgotten nor repeated.
The museum’s existence serves not only as a memorial but also as an educational tool, raising awareness about genocide and human rights abuses worldwide.
What to Expect When Visiting
Visitors to Tuol Sleng will find an emotionally powerful experience. The museum features the original prison cells and classrooms converted into holding areas, complete with shackles and preserved torture instruments.
Thousands of haunting black-and-white photographs of victims, taken by prison guards, line the walls, each face a testimony to the lives lost. Exhibits include survivor testimonies, original documents, and personal belongings of prisoners. A permanent exhibition also details the rise and fall of the Khmer Rouge regime, providing critical historical context.
Visitor Information
The Tuol Sleng Genocide Museum is located on Street 113 in central Phnom Penh, making it easy to access by tuk-tuk, taxi, or guided tour. It is typically open daily, though visitors should check for closures on national holidays.
Modest dress and respectful behavior are expected, as this is a site of remembrance. Audio guides and guided tours are available in multiple languages, offering deeper insight into the stories behind the exhibits.

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