Drive to the Killing Fields of Choeung Ek (16 km south of Phnom Penh). Between 1975 and 1978 about 17,000 men, women, children and infants (including nine westerners) detained and tortured at S-21 prison were transported to the extermination camp of Choeung Ek. They were often bludgeoned to death to avoid wasting precious bullets. Fragments of human bone and bits of cloth are scattered around the disinterred pits. Over 8,000 skulls, arranged by sex and age, are visible behind the clear glass panels of the Memorial Stupa, which was erected in 1988. Return to Phnom Penh. Visit the notorious Tuol Sleng Museum. In 1975 Tuol Svay Prey High School was taken over by Pol Pot’s security forces and turned into a prison known as Security Prison 21 (S-21). It soon became the largest such center of detention and torture in the country. More than 17,000 people held at S-21 were taken to the extermination camp at Choeung Ek to be executed; detainees who died during torture were buried in mass graves in the prison ground. Room after room the museum displays photographs of men, women and children covering the walls from floor to ceiling; virtually all the people pictured were later killed. Visit the Russian Market (Psah Tuol Thom Pong), a lively outdoor market where you will find antiquities, silver and gold jewelry, gems, silk, kramas, stone and wood carvings, as well as T-Shirts, CDs and other souvenirs.