Divide the square site into a grid of equal squares (padas), most often 8 × 8 = 64 or 9 × 9 = 81, and place every part of the building according to the grid.
64 padas (maṇḍūka) or 81 padas (paramaśāyika)
The sanctum over the centre
Place the garbhagriha (the small dark chamber that houses the image) over the Brahmasthana, with its walls on the ring of the gods and its door on the axis, usually to the east.
The garbhagriha (“womb-house”) is deliberately small, thick-walled and dimly lit, a cave in the heart of an artificial mountain. The image or linga stands at the exact centre of the diagram; the tower rises over it on the same axis, so that the building is organised along a vertical line through the sacred point as well as along the horizontal path from the door.
Related rules
Imagine the vāstupuruṣa lying face down on the diagram with his head in the north-east and his feet in the south-west, held down by the gods who occupy the padas; do not place walls, pillars or doors on his vital points.
Read the diagram from the centre outward: Brahmā at the heart, then a ring of the gods, a ring of human concerns, and on the outside the lesser spirits; the holiest function goes at the centre and the most worldly at the edge.
81 padas = 9 (Brahmā) + 16 + 24 + 32
Provide a path for circumambulation (pradakshina) in the clockwise direction, keeping the sacred object on the right, and enclose it with a railing that separates the sacred ground.
Break each face of the square sanctum into projections (rathas), three, five, seven or more, that step forward towards the central one, and carry them up unbroken through the wall and the tower.
tri-ratha 3 · pancha-ratha 5 · sapta-ratha 7 projections per face
Lay the halls along the east–west axis in front of the sanctum (porch, hall, great hall, vestibule), each larger and more lofty than the one before, so that the roofs rise in a continuous range to the shikhara.
Cite this page Chris Paton, “The sanctum over the centre”, The Textbook of Architecture, https://textbookofarchitecture.com/rule/sanctum-brahmasthana. Text, drawings and models licensed under CC BY-NC 4.0.