"The Pope," says Vasari, "approved his model, which reduced the cathedral to smaller dimensions, but also to a more essential greatness.

He discovered that four principal piers, erected by Bramante and left standing by Antonio da Sangallo, which had to bear the weight of the tribune, were feeble.

These he fortified in part, constructing two winding staircases at the side, with gently sloping steps, up which beasts of burden ascend with building material, and one can ride on horseback to the level above the arches.

He carried the first cornice, made of travertine, round the arches: a wonderful piece of work, full of grace, and very different from the others; nor could anything be better done in its kind.

He began the two great apses of the transept; and whereas Bramante Raffaello, and Peruzzi had designed eight tabernacles toward the Campo Santo, which arrangement Sangallo adhered to, he reduced them to three, with three chapels inside.