View of the vault with "Caesar Dictates His Commentaries" in the center

The decoration of the vault is the work of Felice Giani, who in 1812 made six medallions depicting the Tutelary Gods of the Roman Empire (Jupiter, Neptune, Cybele, Mars, Minerva and Hercules) emerging from the characteristic "blue Wedgwood" background, frequently used in that period by the artist, and groups of winged Victories, made with the suggestive 'fake mosaic' technique in a refined accord of the gradual shades of white and gold. At the center of the vault emerges the large painting on canvas by Pelagio Palagi depicting Julius Caesar called the Commentaries, an episode taken from the Plutarchian biography of Julius Caesar, interpreted and updated by the artist through the attribution to the Roman leader of the features of Napoleon.