Cacus

Region/Culture: Southern Europe
Mythos: Roman Mythology
Primary Type/Nature: Monsters and Beasts
Mythical Attributes: Breathes fire and smoke, possesses the strength of a giant, and steals through stealth and deliberate misdirection.
Role in Mythos: A flesh-eating monster of the pre-Roman Aventine Hill whose killing by Hercules is bound up with the founding of Rome’s Ara Maxima.
Relation to Humans: He preyed on the people of the valley below his cave, feeding on human flesh and nailing the heads of his victims to his doors. His defeat cleared the future site of Rome and was commemorated by an altar that became the center of the city’s cattle market.

The doors of the cave were studded with human heads, set into the stone like trophies, and the rock around them stayed black with old smoke. Travelers who climbed the wooded slope above the Tiber learned to read that smell from a distance, charred wood and something worse beneath it, and the wise ones turned back. The hill was not yet Rome. It was a place where a thing lived that ate the people who came too close.

That thing was Cacus, and the Romans remembered him as a son of Vulcan, the smith-god of the forge. From his father he took fire. When he opened his mouth he did not roar so much as exhale a furnace, and the oldest poets gave him three separate throats, each one breathing flame and smoke, so the air in front of him shimmered and stank of sulfur. He was huge, half a man and half a brute, with a body too large to be human and a face the stories never quite settle into a single shape. Some accounts strip the monstrosity away entirely and make him only a savage local chieftain, a cattle-thief with a stronghold on the hill. The grander versions keep the fire.

He survived the way predators do, by patience and by hiding what he had done. He hauled his kills up the slope, fed on their flesh in the dark, and kept the skulls where everyone could see them, a warning posted in bone. Then Hercules came through, driving a herd that was not his by birth either.

The hero was on the long road home from the far west, where he had killed the three-bodied giant Geryon and taken his magnificent red cattle. He stopped to rest in the valley below the Aventine and let the herd graze while he slept. Cacus, watching from his cave, could not let such animals pass. He crept down and stole eight of the finest, four bulls and four cows, and here his cunning showed itself: he dragged them backward by their tails, so every hoofprint pointed away from his lair. Anyone tracking the missing cattle would follow the trail in exactly the wrong direction.

It nearly worked. Hercules woke, counted the herd, found it short, and could make no sense of tracks that led only outward. He gave up and began to move the rest of the animals on. As the herd shuffled past the foot of the hill, one of the cattle shut inside the cave answered the lowing of the cattle outside, and the sound came up out of the rock. That was the whole undoing of Cacus, a single bellow he could not silence. In some tellings it is his own sister, the fire-keeping goddess Caca, who gives him away instead.

What followed was not a clever duel. Cacus bolted for his cave and dropped a boulder across the mouth of it, a stone so vast that his father’s craft must have hung it ready on iron chains. Hercules could not shift it, so he climbed the mountain and tore the top off the ridge, ripping stone loose with his hands until the roof of the lair stood open to the sky and the dark hollow lay exposed like a robbed grave. Cacus filled the pit with fire and black smoke, blinding the hero, vomiting his father’s flames up out of the dark. Hercules answered with whatever the mountain gave him, branches and rocks the size of millstones, and then he went down into the smoke and got his hands on the giant. He did not let go. Virgil says he twisted the throat until the eyes burst from the skull and no blood was left in it. The fire went out.

The people of the valley came up the hill afterward and found they could breathe. Their king, Evander, an old exile from Greece, honored the stranger who had cleared the monster from their door, and Hercules raised an altar on the spot. The Romans called it the Ara Maxima, the Greatest Altar, and the Forum Boarium, the cattle market of the city, later grew up around it. The hero ate his fill of the recovered herd and walked on. A god had passed through, killed the thing in the cave, and left an altar where its smoke used to rise.

His strength was the obvious thing: the inherited fire, the size that let him drag full-grown bulls one-handed, the low animal patience that let him wait above a sleeping man and take only what he could hide. His weaknesses ran underneath all of it. He was a thief, and thieves are undone by the small thing they overlook. He thought in terms of tracks and trails, of fooling an eye, and never reckoned that a stolen cow would simply call out to the ones it had been taken from. Cornered in his own cave, his fire could blind but not save him, because the strength on the other side of the boulder did not need to see. He had built his whole life around concealment, and in the end he was found by a noise.

Frequently Asked Questions

Who is Cacus in Roman mythology?

Cacus is a fire-breathing giant of Roman mythology, the son of the smith-god Vulcan. He lived in a cave on the Aventine Hill before Rome was founded, ate human flesh, and was killed by Hercules.

How did Hercules kill Cacus?

Hercules tore open the roof of Cacus’s cave after the giant blocked the entrance with a huge boulder, then strangled him while Cacus spewed fire and smoke. In Virgil’s account Hercules gripped the throat so hard that Cacus’s eyes burst from his skull.

Why did Cacus steal Hercules’ cattle?

Cacus coveted the magnificent red cattle that Hercules had taken from the giant Geryon and was driving home past the Aventine. He stole eight of them and dragged them backward by their tails so the hoofprints would point away from his cave, but a cow trapped inside lowed back to the herd and gave him away.

What did Hercules build after killing Cacus?

After slaying Cacus, Hercules raised the Ara Maxima, the Greatest Altar, on the spot. The Forum Boarium, the cattle market of ancient Rome, later grew up around this altar.

Was Cacus a monster or a man?

It depends on the source. Virgil, Ovid, and Propertius describe Cacus as a monstrous fire-breathing giant, while Livy and Dionysius of Halicarnassus portray him as a savage human brigand or local chieftain rather than a true monster.