A LOST CRAFT
The Mystery of Cham Brickwork at My Son
The Cham carved ornament into fired brick and joined their towers with almost no visible mortar. A thousand years on, no one can fully explain how.
See My Son options on GetYourGuide ↗Carved into the brick, not the stone
The first thing to understand about Cham building is that the ornament is cut into the brick itself. In many Indian and Khmer temples, decoration is carved in stone and set against plainer walls; at My Son the Cham fired their bricks, raised the towers, and then carved dancers, foliage and deities directly into the assembled brick face. Sandstone was used sparingly, for a few lintels and pedestals. Carving hard-fired brick crisply, without the surface crumbling, is genuinely difficult — yet the Cham did it at scale and to a very high standard. This single choice defines the look of My Son and sets Cham architecture apart from its neighbours.
Walls without visible mortar
Look closely at a well-preserved Cham wall and you will struggle to find the mortar lines. The bricks fit so tightly, with joints so thin, that the wall can read almost as a single mass — in places it is said to be hard to slip a knife blade between them. How the Cham achieved such fine, durable bonding is one of the enduring puzzles of Southeast Asian archaeology. Ordinary lime mortar would leave obvious seams and tends to weather differently from brick; here the joins are nearly invisible and have held, in a humid tropical climate, for a thousand years and more. It looks less like laying bricks than like growing a single brick object.
The theories: resin, brick-paste and firing
Researchers have proposed several explanations, none universally accepted. One widely cited idea is that the Cham used a vegetable adhesive — resin or oil from local trees such as the dầu rái — perhaps mixed with brick powder, curing into something very close to the brick itself. Another proposes that towers were built from partly dried bricks and then fired as a whole, effectively baking the structure into one piece. A third points to an extremely fine clay-and-brick-dust slurry as the 'mortar'. Modern analyses have leaned toward a resin-and-clay bond, but attempts to fully reproduce Cham walls have had partial success at best, which is why these remain competing hypotheses rather than settled fact.
Why it still isn't settled
Part of the difficulty is that the Cham left no manual — the inscriptions record kings and gods, not construction methods. Part of it is that My Son suffered badly: the war and the tropics destroyed much evidence, and some 20th-century repairs used modern cement that has aged worse than the original brick, muddying the picture. Testing original material is limited by the need to preserve it. So conservators work backwards from surviving walls, chemistry and experiment, narrowing the possibilities without closing the case. It is worth being honest about this on a visit: the confident-sounding 'lost secret of Cham brick' is real in the sense that no one can yet fully reproduce it.
What it means for conservation
The mystery is not merely romantic — it makes restoration genuinely hard. Repairs using modern bricks and cement stand out, weather differently, and can even damage the original fabric, as some earlier interventions showed. Recent conservation has therefore tried to recover traditional methods: firing bricks to match the old ones and seeking bonding techniques closer to the Cham originals. Progress is slow and much is still trial and error. This is one reason parts of the site are fenced or scaffolded, and why the towers that survive are treated so carefully. Watching conservators wrestle with a thousand-year-old technique is, in its own way, part of the My Son story.
How to see it for yourself
You do not need to be a specialist to appreciate the craft. Get close, where the paths allow, to a well-preserved wall in the B–C–D group and look for the near-seamless joints and the ornament cut straight into the brick — the sharp floral bands, the faces, the dancers. Compare a Cham original with any obviously modern repair nearby and the difference in colour, fit and finish becomes clear. Early-morning light rakes across the brick and throws the carving into relief, which is one more reason the dawn visit rewards. Bring a little patience and you will see why this humble red brick has kept scholars arguing for over a century.
More things to do nearby
Still deciding early-morning tour or your own ticket?
Leave your email and roughly when you're travelling — we'll send a short rundown of how the early-morning tours, boat-return trips and entry-only tickets compare from Hoi An and Da Nang.