The courtyard of Palazzo Giustiniani features ancient marble relieves, most coming from Villa Giustiniani, outside Porta del Popolo. These marble stones were moved during the renovation works of the late 1670's ordered by Carlo Benedetto Giustiniani.

Their themes are mythological, decorative or symbolic. From the left clockwise, we can see a representation of Heracles's deeds, a sarcophagus front with Muses, another sarcophagus front with a sea thiasus, a sarcophagus fragment with seasonal genii who bring a medallion with the dead's portrait, a sarcophagus with Dionysus's triumph, a fragment with a sea thiasus, a sarcophagus with the myth of Pentheus, a sarcophagus with the abduction of Persephone and, finally, a sarcophagus with the myth of Orestes.

The decoration of the courtyard also includes a remarkable marble fountain surmounted by the coat of arms of Pope Pius IX.