Rhea Silvia

"Oh, my dear! I’m afraid you’ve mistaken me for someone else! My name is Rhea Silvia. I was the mother to Romulus and Remus, thousands of years ago. But you’re so kind to think I look as young as the 1950s."

- Rhea Silvia to Annabeth Chase

Rhea Silvia (also known as Ilia) was the mythical mother of the twins Romulus and Remus, who founded the city of Rome.

History
She was the daughter of Numitor, king of Alba Longa, and descended from Aeneas. Numitor's younger brother Amulius seized the throne and killed Numitor's son, then forced Rhea Silvia to become a Vestal Virgin, a priestess of the goddess Vesta. As Vestal Virgins were sworn to celibacy for a period of thirty years, this would ensure the line of Numitor had no heirs.

However, when the god Mars had discovered her in the forest he seduced her, which would latter cause Rhea Silvia to give birth to the twins Romulus and Remus.

When Amulius learned of the birth he buried Rhea Silvia in the ground to suffocate and die and ordered a servant to kill the twins. Nervertheless, the servant showed mercy and set them adrift on the Tiber River, which, overflowing, left the infants in a pool by the bank. There Lupa, who had just lost her own cubs, found them and cared for them. Tiberinus saved Rhea Silvia before she could die and married her.

Romulus and Remus went on to found Rome, overthrow Amulius, and reinstate Numitor as King of Alba Longa.

The Mark of Athena
Rhea Silvia and her husband help Annabeth Chase to start off her quest for the Athena Parthenos in Rome, Italy. While driving to the starting point of the journey, Rhea talks about the vast history of Rome, telling Annabeth about how buildings have changed over the years and how her husband saved her children on his shores.

Appearance
She is mistaken for and repeatedly compared to Audrey Hepburn.

Trivia

 * She's one of the few mortals/legacies to have become a goddess after her death, others being Heracles and Hersilia, wife of Romulus.
 * She shares her first name with Rhea, the wife of Kronos.