Shape each block of the finest walls to the irregular outline of the stones already laid, grinding the joints until they close without mortar; let the stones be as large and as many-sided as they come.
Rules · Walls · Materials · Proportion
Coursed ashlar for the holiest places
For the most sacred buildings lay rectangular blocks in level courses that diminish in height towards the top of the wall, with pillowed faces and joints closed without mortar.
The curved wall of the Coricancha, the temple of the Sun in Cuzco, now under the church of Santo Domingo, is the classic example: fine andesite blocks in perfectly level courses, the lower ones taller than the upper, the whole wall battered. Coursed ashlar demanded even more work than polygonal fitting, since every bed had to be dead level; the Inca reserved it for temples and royal buildings.
Related rules
Give doors, windows and niches sides that lean inward, so that each opening is narrower at the top than at the bottom, and span it with a single stone lintel.
top width ≈ ⅘ of bottom width
Batter every wall a few degrees, thicker at the foot than at the top, and round its outer corners.
batter ≈ 3–5°
Cite this page Chris Paton, “Coursed ashlar for the holiest places”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/inca-coursed-ashlar. Text, drawings and models licensed under CC BY-NC 4.0.