Architecture stays. Environment changes.
Amended D-330 By floor: lower 1–30, middle 31–70, upper 71 and up, with no end. The First Breach (21–30) is where the first light enters, at the top of the lower Tower. This is how the altitude looks, not a gameplay band (D-021).
Lower
Mostly intact exterior; vast interiors disappear into darkness; same ivory stone reads dirty grey/charcoal; human lanterns create tiny islands of visibility; damp masonry, drips, pools, small streams; mostly dry channels; sparse black-green moss.
Middle
Catastrophic breaches admit sunlight and rain. Ancient channels catch water; waterfalls form accidentally. Stone reads warm yellow-ivory. Moss, vines, grasses, shrubs and occasional trees colonize wet/light areas. This is an ancient interior colonized through its wounds, not a forest biome.
Upper
Same architecture; exterior envelope catastrophically absent; open sky/clouds; chalk-white ivory stone; sparse pale moss/lichen; long thin falls; increasingly unreliable structural physics; some architectural fragments float. Never default to heaven/Olympus/celestial palace.