Twelve-Angled Stone
Twelve angles cut into a 6-tonne block, fitted without mortar — no blade fits between the stones.
- Location
- Peru · Americas
- Civilisation
- Inca
- Period
- ~1400–1500 AD (Inca)
- Technique
- Cyclopean polygonal masonry without mortar
- Studies
- Protzen corpus (Inca masonry)
the state of research converges — open to revision. A revisable snapshot of the state of research, never a judgement.
→ Show on the mapThe elements of the site
Where the site is
13.516° S, 71.976° W · satellite view
What science says
A single block of green diorite, ~6 tonnes, with 12 polished angles that interlock with the neighboring stones without mortar — the fit is so tight that a sheet of paper cannot pass through it.
Carving into multiple angles is an anti-seismic solution: the polygonal blocks interlock and "dance" then settle back into place during earthquakes, without any binder.
J.-P. Protzen (1985) experimentally reproduced these joints by hammering with stone pounders and trial-and-error fitting — without iron tools.
Inca masonry is a distinct indigenous tradition from Tiwanaku (Protzen & Nair, 1997); the wall belongs to the Hatunrumiyoc palace, listed as Cultural Heritage of the Nation (Peru).
What remains unexplained
Related to
Studies & sources
Explore the Inca civilisation
~1200 – 1533 AD · Andes (Peru, Bolivia, Ecuador, Chile) — 3 sites in the atlas
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