The Statue of Ares is a human-sized bronze statue of the war god Ares chained in the Temple of Fear. Though it was initially believed that the Spartans wanted to keep the spirit of war in their city, the chained statue of Ares held the makhai so that their terrible power would not be unleashed upon those who haven't felt fear.
Entering the Temple of Fear to find the "chained god's heartbeat" for the physician's cure, Piper McLean and Annabeth Chase find the statue of Ares wrapped with bronze chains and anchored to the floor. They hear the sound of its "heartbeat", described to be like a "drumbeat ... with a metallic echo".
During the fight with Mimas, Piper prays to Phobos and Deimos, offering them her cornucopia as a sacrifice. She uses the horn to take off the statue's head, releasing the makhai in a "firestorm of emotions". The statue itself ultimately disintegrated into dust.