Aeneas and the Omen of the Sow. To find out more about Aeneas and the omen of the sow, see this British Museum article:, see this Wikipedia article: link; for information about the image: image source.
As famously told in Vergil's Aeneid, the Trojan exile Aeneas finally reached Italy and experienced a vision of the river god Tiberinus during the night; Tiberinus told Aeneas that Aeneas's son Ascanius would found the great city of Alba on the location where they saw a white sow with thirty piglets. Sure enough, the next day, Aeneas and Ascanius found the promised pig, which they sacrificed to the goddess Juno to solicit her favor. You can read the whole story in Book VIII of the Aeneid.