In Zoroastrian belief, the human body at death is considered unclean, and to avoid pullution of the sacred elements of earth, water, or fire, Zoroastrian funerary practices require that bodies of the dead be laid atop a structure known as the Tower of Silence. The towers are imposingly tall, hollow cylinders of stone, whose function is to expose bodies to vultures and sunlight. When a body is reduced to bones, they are removed to the deep centers of the towers.

Because practice depends upon vultures to make quick work of the bodies of the dead, the practice may have to be abandoned, as in recent years the vulture population has declined precipitously due to environmental contaminants.