Four rules the mu’allim never broke.

Walls thick enough to cool a room without a fan.

Sixty to eighty centimetres of hand-formed adobe — the desert’s only honest insulation, and the reason At-Turaif still breathes in August.

One door painted, one colour only.

Cobalt blue marks the threshold and nothing else. Spend the pigment where it matters; let the mud carry the surface area.

Carve the grille, don’t hang the curtain.

The cross-and-diamond window cut into the wall ventilates, shades and decorates in a single move — three jobs, zero ornament.

Crown each roofline with triangles, never curves.

The saw-tooth merlon is the Najdi signature against the sky — six teeth read as a wall, twelve read as a palace; never fewer than four.