Tartarus

Tartarus was both a primordial deity and a place — the lowest region of the cosmos. It was described as being so deep that an anvil dropped from the surface would fall for nine days before reaching it. Bronze walls surrounded it, and a triple layer of night hung over its entrance.

After the Titanomachy, Zeus imprisoned the defeated Titans in Tartarus, setting the Hundred-Handed Ones as guards. It also became the place of punishment for the greatest offenders against the gods. Tantalus stood in a pool of water beneath fruit trees, forever hungry and thirsty as both receded from his reach. Sisyphus rolled a boulder up a hill only to watch it roll back down, for eternity.

Ixion was bound to a flaming wheel that spun forever. The Danaids, who had murdered their husbands, were condemned to fill a bottomless basin with water carried in leaky jars. Tartarus represented the Greeks' vision of ultimate, eternal punishment — justice carried to its most extreme conclusion.