New York City
Half-Blood Hill is one of the hills surrounding the valley where Camp Half-Blood is located. It is well known for being the place where Thalia gave her life to save her friends and where her pine tree is (in fact, it was named "Half-Blood Hill" because Thalia gave her life there). After several automatons, including the bronze dragon, Thalia's tree successfully guarded the hill and kept monsters out. The Golden Fleece now protects the hill, since the tree no longer uses Thalia's spirit. Peleus, the dragon, guards the Golden Fleece. Mortals and monsters cannot go past the hill's magic borders, unless one of the campers, Chiron, or Mr. D allow them in. To mortals, Half-Blood Hill is a strawberry farm.
On Half-Blood Hill, Percy fights the Minotaur after the Minotaur had stolen his mom, Sally Jackson. Half-Blood Hill appears a second time when Percy begins his first quest to recover Zeus' stolen Master Bolt with Annabeth Chase and Grover Underwood, a satyr and Percy and Annabeth's best friend and protector.
Half-Blood Hill is shown in the film at nightfall after Percy, Grover, and Sally Jackson, Percy's mortal mom, arrive by running from Percy's first step dad's car (Gabe Ugliano's damaged Camaro '78) which was destroyed by the Minotaur. It has a sign over the entrance proclaiming Camp Half-Blood which is lit up at night by automatic flames.
Half-Blood Hill is shown at daylight when it is attacked by two celestial bronze Colchis Bulls, automatons made by Hephaestus, while the magical border that it holds is breaking down (it was later discovered by Percy that Luke had fed snake poison to Thalia's Tree). Percy tries to help Clarisse La Rue, a demigod daughter of Ares, fight the bulls but he gets a little bit injured, forcing Annabeth to allow his cyclops half-brother and son of Poseidon, Tyson, to go into camp and help fight the Colchis Bulls effectively.
Annabeth and the other camp members with the exception of the Ares cabin (until later on to help fight the drakon) leave Camp Half-Blood, they depart from Half-Blood hill in three Delphi Strawberry Co. (Camp Half-Blood's cover name) vans to meet Percy at the front steps of the Empire State Building.
Percy is shown a vision of the past where Hermes and Luke's mortal mother, May Castellan is at the steps on the porch of the Big House at Camp Half-Blood talking to Chiron about whether Luke's mother should be holding the Oracle's body or not. Hermes tried to talk her out of it, but his objections made no effect on her decision. Reluctantly, Hermes agrees to her idea and allows her to go into the Big House Attic where the Oracle of Delphi's mummified body is located in.
Hermes and Chiron thinks all is fine while they are waiting on the porch of the Big House patiently, until they hear a scream and light flashing through the Big House Attic's windows. Later, Hermes realizes that he was correct before because he realized that the Oracle was under a curse (or possibly) set by Hades on a grudge against his brother Zeus for killing Maria di Angelo.
Percy is told on Half-Blood Hill by another cabin member that his pegasi, Blackjack, was used (by force) by a mortal girl, Rachel Elizabeth Dare, as transport to Camp Half-Blood on a hurried mission (to be the new carrier for the Oracle of Delphi after Hades' curse over the oracle was raised) after the Battle of Manhattan.
Percy, Annabeth, Grover, and all of the other campers hurry back to Camp Half-Blood by the camp's three vans after Percy was told about Blackjack being used as "hurried transport." Once there, Percy hurries to the porch of the Big House and meets Blackjack outside. Blackjack tells him that he couldn't stop Rachel for she insisted to take him without telling Percy at all which Percy says that it really doesn't matter to him.
Half-Blood Hill is only seen once when Jason Grace goes on a quest to save Hera, also known as Juno, the goddess of marriage, Queen of heaven, and sister-wife of Zeus, from Porphyrion the leader of the Giants with Piper McLean, a daughter of Aphrodite and Leo Valdez, a son of Hephaestus.