Anyone who's read the Percy Jackson books by Rick Riordan probably knows what Camp Half-Blood is, but surprisingly we get quite a few users here who haven't read the books but are here because they are interested in Greek myth. So I will take some time to explain a bit about Camp.
"A safe sanctuary for demigods, a place to train."
The Greek gods love to meddle with mortals and have kids, but they also have strict rules about what level of interference they are allowed to have in their children's lives. Unfortunately that leaves their children out in the world to fend for themselves, and with monsters sniffing them down to kill and even eat them, the world is a dangerous place for demigods. So the gods got together and made Camp a secret area hidden on Long Island New York, America.
The camp is protected with a barrier that monsters can't pass, and neither can mortal without permission from the camp director. Here at this special camp, demigods can either stay for summers and holidays, or year round, to train to fight, learn about what it means to be a demigod, meet other demigods and various mythological beings, go on quests, and above all else, be safe from harm while within the borders.
The Camp Director is Alexander the Great, well his soul trapped inside an Automaton at least, as his physical body died a very long time ago. He's been promised a place in Elysium if he agrees to be the camp director for a hundred or so years, he grudgingly agreed, but often has a short temper with the campers or ignores them entirely when he can.