The modern-day towers, which are fairly uniform in their construction, have an almost flat roof, with the perimeter being slightly higher than the centre. The roof is divided into three concentric rings: the bodies of men are arranged around the outer ring, women in the second circle, and children in the innermost ring. 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 – with run-off rainwater – runs through multiple coal and sand filters before being eventually washed out to sea.