A Buddhist stupa at the Choeung Ek Genocidal Center near Phnom Penh, Cambodia honors the memory of an estimated 17,000 people who were murdered at this spot under the Khmer Rouge regime of 1975 to 1979. Choeung Ek is the best known of the more than 300 mass execution sites in Cambodia that came to be known as the Killing Fields. Most of those who passed through Tuol Sleng prison in Phnom Penh were later murdered and buried here. March 1, 2012.