Borobudur

Why this is extraordinary

Borobudur stands on a hill in the Kedu plain of Central Java, between the Progo and the Elo. You walk up it. The World Heritage listing places it in the 8th and 9th centuries, in the Sailendra period, and says the monument was built in three tiers around a hill that was already the natural centre. The stone is andesite, a grey volcanic rock. About 55,000 cubic metres of it came from nearby quarries and from the bed of the Progo. The usual count of blocks is on the order of two million. They were laid with no mortar. Knobs seat in holes. Dovetails lock other joints. The conservation bureau gives a common block as about 40 to 50 centimetres long, 30 to 40 thick, and 20 to 25 high.

The base is about 123 metres square. Five square terraces rise on it, then three round platforms. Seventy-two perforated stupas stand on those platforms, and one central stupa brings the top to about 35 metres above the ground. Counting the base with the five terraces is how the plan is also told as six square stages under three circles. Reliefs cover about 2,520 square metres. The usual panel count is 2,672. The usual Buddha count is 504, and 72 of those sit inside the perforated stupas.

A mandala here is a diagram of the cosmos a person walks. A square earth under a round heaven is what that diagram already asks for, and the square galleries sit under the round crown. The stairs run to the cardinal directions. The east door is where the stories begin, and the main approach comes in from the east. Stand there at morning and you can see whether the sun meets that door. No degree is printed in the sources this room uses. On the three round terraces the stupas are a regular count, 32, then 24, then 16, inside the 72. A regular count can be a calendar. It can be a sighting device, an instrument for the sky. It can also be what a mandala already requires, cardinal symmetry and rings of stupas, nothing further. A Mount Meru model already looks up, and an instrument reading is only a stronger version of a building that was never only a room. The hard part is that a count is not a measured alignment until someone surveys the east axis against the sun and the stars and publishes the method. The same integers can be fitted to more than one cycle. A fit without a recorded rule from the builders is a modern grid. No sightline in the sources used here does work this cosmological layout does not already explain. Keep both readings. The cardinal building is certain. An extra astronomical use is possible and, so far, not required.

A hundred carved spouts take the rain off the galleries. In 2010, ash from Merapi, about 28 kilometres east, lay up to 2.5 centimetres deep on the stone and choked the channels. The drainage is a working system. Slurry can stop it.

No foundation charter is cut on the walls. Short labels on the buried foot are in a script of the late 8th and early 9th centuries, and they tell the carvers which scene to cut. Two charters from this plain, 824 and 842, name a Buddhist foundation nearby. They are the closest written dates. They were not found in the masonry.

In 1814 about two hundred workers spent about two months cutting forest and digging earth off the terraces. Not every gallery was opened. The walls were not trusted to stand if the fill came out. The buried foot, 160 reliefs of the law of karma, was recognised in 1885, recorded, and covered again, with a few panels left in view. A later campaign, in the 1970s and early 1980s, took the casing apart and rebuilt it.

The century, the volcanic stone, and the dry joints are a built monument with a Buddhist program. Still open are the encased foot, an earlier structure in the hill, a lake at the foot, and a stricter reading of the plan as a sky instrument. That is the part that changes when the walk is asked to be more than one thing.