Big House

The Big House is a large blue house which serves as the main administrative building at Camp Half-Blood. Mr. D, Chiron, and other Camp Half-Blood staff members including all cabin leaders usually have their meetings there and it serves as the infirmary for the camp. There are four floors, a basement and an attic in the big house. It also has a fireplace in which it is lit up depending on the mood of all of the demigod campers. It is home to Mr. D, Chiron and Argus. All new campers go here to see the orientation film, as well as meet Chiron and Mr.D. In The Lost Hero, Chiron invites Piper McLean, daughter of Aphrodite, into his office where he leaves Piper to a full web video in which she talks with her dad, Mr. McLean, her satyr protector, Hedge, and her father's new assisstant.

History
The Big House was part of Camp Half-Blood for a long time. It has held the Oracle's body ever since she died (before Rachel was made the Oracle). It had red paint during the 80s' through the early 90s' but has since been painted blue.

Infirmary
Wounded demigods would usually go here for treatment or healing. Most likely staffed by the Apollo cabin because their father, Apollo, is the god of healing besides being the god of the sun, music, and the arts. In The Lightning Thief movie, there is an infirmary but no mention of a Big House is made.

Attic
The attic is the home of many things. It held many trophies that demigods got from monsters and other situations such as long ago quests that many different demigods have taken. The attic used to hold the Oracle's body (or what was left of it), which told prophecies for the quests of the campers.

Deck
Where Chiron and Dionysus play Pinochle most of the time.

Chiron's office and apartment
Where Chiron has his room and does official business from his desk; has a record player and a full screen video (where the orientation film watched by all new campers is located). He also has a boom box (with the most horrible music from Italy with a bunch of violins and some guys singing opera in italian) that was used by Annabeth and Percy to scare away the Stymphalian Birds. Chiron's apartment is also located here as he lives and gives training to Percy and other demigods at camp.

Basement
The only mention of the basement is when Chris Rodriguez was taken care of in The Battle of the Labyrinth by Clarisse.