The Carthaginian Serpent was a 120 foot snake that emerged from the River Bagrada in North Africa to confront Roman General Marcus Atilius Regulus and his troops during the First Punic War. Eventually it was destroyed when the Legion buried it in rocks.
Apollo, Meg and Leo face this monster in when traveling to Commodus' lair in Indianapolis via the Canal Walk. They are forced to abandon ship but Meg manages to blind the serpent in one eye before it is about to crunch her as it did to their pedal boat. Apollo notices bricks from a nearby condominium coming lose and shouted to collapse it on the serpent, killing it and freeing Meg before the gate Leo opened closed again.
The serpent's skin was glistening serpentine flesh, green and brown ridged with serrated dorsal fins. Its triangular forehead was wide enough to provide parking for a compact car, its eyes glowed orange like the ghost of Agamethus, the breath from its vast red maw smelled worse than Hephaestus's work shirts.