S-21 Prison, also known as Tuol Sleng, was a former high school in Phnom Penh, Cambodia, that was converted into a detention and torture center during the Khmer Rouge regime from 1975 to 1979. It is estimated that around 14,000 people were imprisoned there, with only a handful surviving. The facility was notorious for its brutal treatment of prisoners, who were subjected to severe torture and forced confessions. Today, S-21 Prison serves as a museum and memorial to the victims of the Khmer Rouge, led by Pol Pot. The site educates visitors about the atrocities committed during this dark period in Cambodian history and honors the memory of those who suffered and perished there.