Tuol Sleng or S-21 operated as an extermination center for those deemed to be enemies of the Khmer Rouge state. In the four years it operated an estimated 20,000 people were tortured and then executed. There are 12 known survivors. As Milton Osborne observes in his book Phnom Penh: A Cultural History: “If ever Hannah Arendt’s “banality of evil” seemed justified, it is surely in relation to these outwardly unimpressive set of buildings.”
Originally, the buildings housed the Tuol Svay Prey high school – the school’s original name meant “Hillock of the Wild Mango”; its later designation means “Hillock of the Sleng Tree.” The conditions of S-21 were horrendous, a fact that remains vividly apparent to visitors today. In converting an anonymous set of four school buildings into a torture prison the regime installed a range of restraints, chains, shackles and bars, with bare iron bedsteads used to hold down prisoners while they were tortured.
The Khmer Rouge constructed few (possibly none?) formal building projects to mark their presence on the city. Rather they relied heavily upon the reuse of buildings designed for another purpose for their short tenure. In this sense the museum at Tuol Sleng is one of the few buildings which serves as a monument to their reign.