Petra- “Treasury”

  • I started with the axes of the outer columns. I will call the distance from those axes to the centerline 1 unit, so that the width between those axes is 2 units. The height of the column shafts in the first story is 1 unit, so that this area forms a double square (slightly smaller than the one that you found around the exterior of the composition; more on that below…)

    I stepped in by quadrature, and found the width of the door opening, which is (root2)/4, or .354, in addition to noticing that the right-hand column flanking the door sits further outboard than its pendant to the left.