Mỹ Sơn's kalan towers were raised in fired brick laid dry — no mortar bed, at most a clay slip or resin that has long since gone. The wall went up as solid mass; pilasters, false doors and apsaras were then cut directly into it, and the finished façade was surface-fired to fuse a weatherproof skin.

The system takes its discipline from that sequence. Surfaces are built first and carved second: ornament is recessed into the plane, never applied on top. Colour stays inside one greyed red-brown family, relieved only by pale sandstone and the lichen and wet-season moss that creep across the north faces.