According to Wiggins and Gourley, Shelley spent a year in Genoa after Percy's death and might have been to Genoa's Cathedral of San Lorenzo. 

The latin inscription reads "Jan(us) P(ri)mu(s) rex italie * De Progenie Gigantiu(m)" which shows that Janus was the founder of the citry. 

The Cathedral is picture below, as well as the Latin inscription