Read it through once

The Towers are not tall, but are low in proportion to their circumference, like a gasometer. If you should fill a gasometer half way up with solid granite masonry, then drive a wide and deep well down through the center of this mass of masonry, you would have the idea of a Tower of Silence. On the masonry surrounding the well the bodies lie, in shallow trenches which radiate like wheel-spokes from the well. The trenches slant toward the well and carry into it the rainfall. Underground drains, with charcoal filters in them, carry off this water from the bottom of the well.