Pelion is a mountain at the southeastern part of Thessaly in central Greece, forming a hook-like peninsula between the Pagasetic Gulf and the Aegean Sea. In Greek mythology, Mountain Pelion was the homeland of Chiron the Centaur, tutor of many ancient Greek heroes, such as Jason, Achilles, Theseus and Heracles. When the giants Otus and Ephialtes attempted to storm Olympus, they piled Mount Pelion upon Mount Ossa, which became a proverbial allusion for any huge but fruitless attempt.