Tuol Sleng Genocide Museum

Phnom Penh, Cambodia

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Tuol Sleng Genocide Museum in Phnom Penh, Cambodia, occupies the former Tuol Svay Prey High School, converted by the Khmer Rouge into Security Prison 21 (S-21) from 1975 to 1979, where an estimated 20,000 people mostly intellectuals, officials, and ordinary citizens were tortured, interrogated, and executed as perceived enemies of the regime.

Preserved largely as discovered by Vietnamese forces in 1979, the site features grim classrooms turned into tiny brick cells, torture chambers with iron beds and bloodstains, and walls displaying thousands of haunting black-and-white prisoner photographs alongside survivor testimonies and paintings by Vann Nath, one of only 12 known survivors.

Opened as a museum in 1980 and now a UNESCO-recognized memory site, it confronts visitors with the Khmer Rouge's atrocities—part of a genocide claiming 1.7-2 million lives—through stark exhibits, mass confession archives, and calls for remembrance to prevent repetition.