Athena Parthenos is a forty-feet-tall statue of the goddess Athena which was once the central figure in the Parthenon of Athens. The Parthenos had the figure of Athena carved from ivory, wearing a gold toga, and holding a statue of the goddess Nike on her palm. The statue's other hand held a shield, with a snake emerging from behind it. Annabeth Chase thought that the Parthenos was a perfect likeness of Athena, and that the sculptor must have met her.
When the Roman Empire conquered Greece, they took the Parthenos as a way of breaking Greece's spirit. As Athena became Minerva, she lost her status as a war goddess; the capture of the Parthenos was seen as an act of belittlement to Athena, and the source of the seemingly eternal conflict between Greek and Roman demigods. According to legends among the Romans, every civil war between the Greeks and the Romans was started by children of Athena. In every subsequent generation after the Parthenos's capture, Athena charged one of her children to recover the statue, by following the Mark of Athena through the city of Rome. The Parthenos itself was protected by Arachne, who wove spider webs around it to contain its power, though the Parthenos was still powerful enough that monsters burrowed up under the floor, leaving only a thin layer of tile and spider webs between Arachne's chamber and a pit straight to Tartarus. All of Athena's children, up to Annabeth Chase, had failed in retrieving the statue.
Annabeth Chase finally succeeds where generations of her siblings have failed. She successfully followed the Mark of Athena to Arachne's chamber. Even though she injured her ankle, she outwitted and trapped the spider in its own woven prison, relating to a line in a prophecy. The Argo II arrives, blasting open the ceiling, and sending debris down the chamber, ruining the floors where Arachne believes leads to Tartarus, and the spider falls into the pit. As Leo Valdez, Frank Zhang, and Jason Grace secure the Athena Parthenos, just barely fitting it inside the ship. However, Annabeth and Percy Jackson are dragged into the pit leading to Tartarus by Arachne.
The Athena Parthenos is in located in the lower deck of the ship where the sick room and stables are. Leo states that he has been trying to find for secret weapons or machinery in the statue, but there is none. Leo is caught holding onto the miniature Nike that is held in Athena's hand.
At the end of the book, Nico, Reyna and Coach Hedge leave to transport the statue back to Camp Half Blood as a way to make amends, although Coach Hedge believes that they should launch it at Gaea as a missile.
Throughout the book, Nico, Reyna and Coach Hedge make a perilous journey through Nico's shadow travel to return the Athena Parthenos back to Camp Half-Blood. They encounter many dangers and shadow traveling so much nearly kills Nico. Eventually, with the help of Pegasus, Blackjack and six other pegasi, they make it to Long Island Sound, but are unable to approach Camp Half-Blood due to Greek onagers around the camp which could shoot them down. For safety, they set down on a yacht and though Pegasus has to leave, he gets Blackjack and the other pegasi to stay and help get the statue the rest of the way. Michael Kahale, Dakota and Leila attempt to arrest them, but Kahale is subdued by Tyson and Dakota and Leila defect. Reyna sends Coach Hedge back to camp with Tyson, Ella and Rainbow due to his wife being in labor and Nico with the other two Romans to stop the onagers while she plans to bring the statue at sunrise. Orion attacks and attempts to destroy the statue and kill Reyna, but with the help of Athena and Bellona, Reyna finally kills him though Blackjack is seriously injured. At sunrise, as the camps are about to go to war, Reyna arrives with the pegasi and the Athena Parthenos and presents it to the Greeks as a gift of reconciliation. The appearance of the statue stops the war and heals the division between Greek and Roman. It also heals the split personalities of the gods, allowing them to come to the Seven's aid against the giants in their Greek forms. Gaea rises, but its revealed that the statue's power is able to hold her back for a little while though she proves too powerful for even the Athena Parthenos to restrain her forever. After Gaea is defeated, the camps officially make peace and the Athena Parthenos now rests on Half-Blood Hill.
- Athena Parthenos means "Athena the Virgin."
- The Athena Parthenos was sculpted by an artisan named Phidias.
- The Statue was stolen by the ancient Romans to break the spirit of the Greeks.
- The Statue has to be returned to Camp Half-Blood by a Roman officer to heal the rift.
- The Athena Parthenos is infused with the power of Athena.
- Annabeth Chase speculates that the statue may have shielded her from falling debris in Arachne's lair as she was completely uninjured, but it may have also just been luck.
- The Athena Parthenos displays a few powers: it is able to shield itself from falling debris, it may have shielded Annabeth, it occasionally glows including when Athena gave Reyna her aegis, indicating she may have done it through the statue or used its power for it. When returned to Camp Half-Blood, it sends a wave of golden energy through the Greek and Roman camps and heals the god's split personality problems.