Phnom Penh, Cambodia ? Skull by human skull, officials dismantled Sunday a key memorial to the atrocities committed by Cambodia’s former Khmer Rouge rulers.

Buddhist monks prayed for the souls of some 300 victims of the communist regime whose remains were part of a map of Cambodia made of skulls and displayed publicly since 1979 as a testament to the regime’s brutality. Museum officials said the skulls were decaying.

The map, held together by wire, was taken apart after the Buddhist ceremony and the human remains placed in a wooden case enclosed by glass.

Hundreds of thousands of Cambodian and foreign visitors to the Tuol Sleng Genocide Museum had viewed the grisly, 129-square-foot wall installation of skulls and bones.

An estimated 1.7 million Cambodians died during the 1975-79 rule of the radical regime because of disease, starvation, overwork and execution. Leader Pol Pot died in 1998 but many of his top lieutenants live freely in Cambodia after reaching defection deals with Prime Minister Hun Sen’s government.

“It left a strong and powerful impression on me,” said Mexican tourist Rosalia Contreras, a 36-year-old dental researcher, after viewing the map of skulls. “I can’t understand why people do this to each other,” she said, tears running down her cheeks.

Youk Chhang, director of the Documentation Center of Cambodia, which has been gathering evidence of Khmer Rouge atrocities for eight years, said he supported the removal of the skull map.

“Cambodians and foreigners should be educated about the tragic past but publicity like this is not necessary. Scientific explanation does more to help people understand,” he said.

The empty place on the wall will be replaced by a large, color map of Cambodia, identifying many of the regime’s mass graves and prisons. A photograph of the skull map will also be displayed.