The ceiling of the Third Corridor, also called West Corridor, painted round 1658-1679 by Giacomo Chiavistelli, Angelo Gori and Cosimo Ulivelli represents some great Florentines and the cities belonging to the Grand Duchy of Tuscany.
Some parts of this ceiling were destroyed in 1762 because of a terrible fire and were thus painted again by Giuseppe del Moro, Giuliano Traballesi and Giuseppe Terreni
In 1506, in Rome, the Hellenistic Laocoon Group was found. The deep impact this group had on contemporary artists is testified by the copy of it Baccio Bandinelli realised between 1520-25. Bandinessi's Laocoon Group is displayed at the very end of this corridor.