Giovanni Cambi says that they were begun at the end of March 1520.

But we first hear something definite about them in a _Ricordo_ which extends from April 9 to August 19, 1521.

Michelangelo says that on the former of these dates he received money from the Cardinal de' Medici for a journey to Carrara, whither he went and stayed about three weeks, ordering marbles for "the tombs which are to be placed in the new sacristy at S.Lorenzo.And there I made out drawings to scale, and measured models in clay for the said tombs." He left his assistant Scipione of Settignano at Carrara as overseer of the work and returned to Florence.

On the 20th of July following he went again to Carrara, and stayed nine days.

On the 16th of August the contractors for the blocks, all of which were excavated from the old Roman quarry of Polvaccio, came to Florence, and were paid for on account.