The ground plan of the monumental chapel corresponds to Brunelleschi's sacristy, and is generally known as the Sagrestia Nuova.

Internally Buonarroti altered its decorative panellings, and elevated the vaulting of the roof into a more ambitious cupola.

This portion of the edifice was executed in the rough during his residence at Florence.

The facade was never begun in earnest, and remains unfinished.

The library was constructed according to his designs, and may be taken, on the whole, as a genuine specimen of his style in architecture.
The books which Clement lodged there were the priceless manuscripts brought together by Cosimo de' Medici in the first enthusiasm of the Revival, at that critical moment when the decay of the Eastern Empire transferred the wrecks of Greek literature from Constantinople to Italy.