A despatch written to the Duke of Parma in September 1545 informs him that the old works were being abandoned, with the exception of the grand Doric gateway of S.
Spirito.

This is described at some length in another despatch of January 1546.

Later on, in 1557, we find Michelangelo working as architect-in-chief with Jacopo Meleghino under his direction, but the fortifications were eventually carried through by a more competent engineer, one Jacopo Fusto Castriotto of Urbino.
VI Antonio da Sangallo died on October 3, 1546, at Terni, while engaged in engineering works intended to drain the Lake Velino.

Michelangelo immediately succeeded to the offices and employments he had held at Rome.

Of these, the most important was the post of architect-in-chief at S.Peter's.