On 17 April 1975 the Tou Svay Prey High School became the main torture and interrogation centre for the Khmer Rouge. The site became Security Prison 21. Many died here under torture and were thrown in mass graves in the school grounds. Those that did survive here were sent to their execution at Choeung Ek, over 20,000 of them. It is believed only seven prisoners survived, all artists that were spared to make busts of Pol Pot. Each murdered victim, man woman and child had their photo taken, and many are on display, along with some of the horrific primitive weapons used to kill them. Entry: $2 entry, or $6 including the audio tour. Open: Tue-Sun 8:00am - 11:00am, 2:00pm-5:00pm, public holidays 8:00am - 6:00pm. Address: On 113 Street, where it meets 330 Street.