Flags are the main component of Capture the Flag. Their capture is the main objective of the game. To prevent their flag from being stolen, a team must defend it. It will switch designs depending on who the owner is. The flags are about ten feet tall and are placed in strategic places in the beginning of each game in order to prevent them from being captured by the opposing team.
When the flag has been stolen by the opposing team, and planted on their territory, it changes into the design of the cabin that captured it and the game is won by that cabin.
The flag of Athena's cabin is gray with a painting of an owl above an olive tree.
The flag of Ares' cabin is blood red with a bloody spear and a boar's head.
The flag used by Camp Half-Blood when playing against the Hunters.
The Hunters have a shimmery silver flag.
- In the Middle Ages, when a fort put its flag upside down it either meant that the defenders were desperate or that the fort had fallen.