Hello

Sebastiano Serlio, 1475-1554, wrote 7 books 'On Architecture and Perspective' .

A contemporary of Palladio and Vignola, he spent much of his career in France working for King Francois I. The first part of his treatise was published in 1537.

Here he is with his compass.

The cover of Book I includes this drawing of builders' tools across the bottom, including a tetrahedron and a cube with diagonals, squares and circles on its face, in the right corner.*

What's the cube about? I didn't know, but I am beginning to find out.

Book III, On Antiquities includes the illustration and measured plan of this temple outside of Rome, now thought to be the Sepulchre of the Cercenni. 

He writes that it was "built partly of brick, partly of marble and to a large extent ruinous."

To read the geometry look at

  1) the square, its diagonals which mark the outside of the temple including the bays;

2) the circle which fits within the square which mark the corners of the temple itself;

3) the square which fits within the circle locating the outside of the walls.

Rotate the first square 90* to make an 8 pointed star. The intersections of the stars points mark the outside corners of the bays.

The inner square (barely visible in red) was not used.

Next the outer square was rotated. It crossed the large square at 8 points. Those points when joined laid out the width of the bays.

The lines set the perimeter of the plan.

The mason had his foundation plan and could set his lines.

 I usually find that the interior geometry of a masonry building is laid out from the inner side of the walls. This is practical: reaching over the walls with lines would not have been easy nor accurate. 

The square and its circle neatly locate the columns which support the vaulting.