The cavern walls on either side of the river are pockmarked with natural weyr formations, and those large enough to house a dragon and rider are all being used. The largest weyrs are located lower down on the cliff walls, while the highest are rather small, rough, and exposed to the unpredictable weather above the sheltered canyon. Thus, it only makes sense that the Shadows reside in the uppermost reaches, while the Knights claim the lower quarters. Stairs? Work is still in progress.