In Greek mythology, the Gigantes (monstrous giants) sprang forth when the blood of Uranus fell upon the Earth. They attacked Zeus and the Olympian gods and to reach their abode they stacked two mountain ranges of Thessaly (the Pelion and the Ossa) on top of each other. The gods asked Heracles for help and together they were able to defeat them. The Gigantes were subsequently buried underneath volcanoes all over the world.
Ovid I, 151.