The four sets of double doors giving entry to the room have heavy pediments supported by scagliola columns, and at second-floor height, grisaille panels depict classical themes.
The wings of the exterior are set in the earthly realm of the donors, while the sculpted grisaille saints represents a movement from the to the heavenly.
Such an origin would explain the grisaille painting on the reverse, as it is characteristic of polyptychs to have both sides of folding panels decorated.