Plural of clerestory; multiple high windows in walls, especially the upper portions of church walls that light the interior.
English plural of clerestory, from Old English clere (clear, bright) + story (level or row). Medieval architecture preserved this term to describe the specifically-placed high windows that fill space with natural light.
Walk into an old cathedral and look up at those impossibly high windows—that's 700-year-old lighting design, and it still works better than you'd think for an ancient building.
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