This is where the campers get their weapons. It is a big metal shed around the side of Athena's cabin. In The Lost Hero, Annabeth helped Piper choose her weapon, which is later a dagger named Katoptris, there. It has quite a large collection of swords, spears, clubs and even shotguns. Every camper gets a weapon, but the Hephaestus' cabin makes their own. The armory is confused as the camp forge.