The Olympians were a race of deities, primarily consisting of a third and fourth generation of immortal beings, worshipped as the principal gods of the Greek pantheon and so named because of their residency atop Mount Olympus. They gained their supremacy in a ten-year-long war of gods, in which Zeus led his siblings to victory over the previous generation of ruling gods, the Titans. They were a family of gods, the most important consisting of the first generation of Olympians, offspring of the Titans Cronus and Rhea: Zeus, Poseidon, Hera, Demeter and Hestia, along with the principal offspring of Zeus: Athena, Apollo, Artemis, Ares, Aphrodite, Hephaestus, Hermes, and Dionysus. Although Hades was a major deity in the Greek pantheon, and was the brother of Zeus and the other first generation of Olympians, his realm was far away from Olympus in the underworld, and thus he was not usually considered to be one of the Olympians. Olympic gods can be contrasted to chthonic gods including Hades, by mode of sacrifice, the latter receiving sacrifices in a bothros (βόθρος, pit) or megaron (μέγαρον, sunken chamber) rather than at an altar.