Tower of Silence

[6][7] The discovery of ossuaries in both Eastern and Western Iran dating to the 5th and 4th centuries BCE indicate that bones were sometimes isolated, but separation occurring through ritual exposure cannot be assumed: burial mounds,[8] where the bodies were wrapped in wax, have also been discovered.

The Byzantine historian Agathias has described the Zoroastrian burial of the Sasanian general Mihr-Mihroe: "the attendants of Mermeroes took up his body and removed it to a place outside the city and laid it there as it was, alone and uncovered according to their traditional custom, as refuse for dogs and horrible carrion".

Another term that appears in the 9th- to 10th-century texts of Zoroastrian tradition (the so-called "Pahlavi books") is dakhmag; in its earliest usage, it referred to any place for the dead.

[2][3] Zoroastrian tradition considers human cadavers and animal corpses (in addition to cut hair and nail parings) to be nasu, i.e. unclean, polluting.

[1][10] To preclude the pollution of the sacred elements: earth (zām), water (āpas), and fire (ātar), the bodies of the dead are placed at the top of towers and there exposed to the sun and to scavenging birds and necrophagous animals such as wild dogs.

The ritual precinct may be entered only by a special class of pallbearers, called nusessalars, from the Avestan: nasa a salar, consisting of the word elements, -salar ('caretaker') and nasa- ('pollutants').

Once the bones have been bleached by the sun and wind, which can take as long as a year, they are collected in an ossuary pit at the centre of the tower, where—assisted by lime—they gradually disintegrate, and the remaining material, along with rainwater run-off, seeps through multiple coal and sand filters before being eventually washed out to sea.

[13][14] The precipitous decline in the vulture population in India due to poisoning has led the Parsi community to explore alternatives to standard dakhmas.

[15] In the Iranian Zoroastrian tradition, the towers were built atop hills or low mountains in locations distant from population centres.

[18] Following the rapid expansion of the Indian cities, the squat buildings are today in or near population centres, but separated from the metropolitan bustle by gardens or forests.

[21] In 2001, Parsi communities in India were evaluating captive breeding of vultures and the use of "solar concentrators" (which are essentially large mirrors) to accelerate decomposition.