a tower of silence, as used by Zoroastrians and Parsis
When we tanked a bunch of Javelins to India in the 60s we stayed for a few days in Bombay (that's what the Indians called it then). There was an avoid area which encompassed their Towers of Silence. We went there on an escorted tour close up to these miniature cooling towers and the park was thick with roosting vultures.
Apparently there was a grid on the top and as the vultures progressed the bones would fall through to be collected at the bottom.