The story of Perseus and Medusa is a classic quest. Perseus leaves home with a mission – to get Medusa's head – and returns when he's completed the task. We bet you know lots of quest stories, like The Lord of the Rings, where Frodo leaves the Shire on a mission to dump the One Ring into Mount Doom, and then returns home again when he's succeeded. Since Perseus' story is a such a traditional quest, it makes sense that Perseus starts out at home (the island of Seriphus), leaves to embark on his adventures, and then returns home to Seriphus when he's achieved his goal.
Seriphus is an island in the Aegean Sea. This sea is a part of the Mediterranean that separates Greece and Turkey. Perseus' adventures take him to some distant, mythical places, including the home of the Graeae, the home of the Nymphai, and the cave of the Gorgons. Perseus even flies over Africa, where he happens upon the Princess Andromeda. Because he journeys to so many far off places, his adventures seem very epic.