Pope Gregory X
In the south aisle is the funerary monument of Pope Gregory X (died 1276), dating to the early 14th century. Another funerary monument in the aisles is that of Ciuto Tarlati (1334), formed by a marble sarcophagus of the 4th century AD and a series of reliefs by Agostino di Giovanni, crowned by a 14th-century fresco.