Tartarus

Pit and personification — the deepest abyss beneath the underworld, as far below Hades as earth is below heaven, ringed by a fence of bronze. Hesiod measures it: a bronze anvil dropped from heaven would fall nine days and reach earth on the tenth, then fall nine more before reaching Tartarus. Prison of the defeated Titans after the Titanomachy, and of Typhoeus after his revolt.