The primate house was part of the Safari Adventure attraction at Nuka-World, where visitors could see a number of primates. It housed at least four gorillas. Cito, a man who was raised by the now-irradiated ghoulrillas after his parents died, calls this area home and wants to protect his family of ghoulrillas from the monsters outside.
The primate house is a small building with two gorilla cages on either side with a small area for zoo visitors in between. Since the Great War, both cages are open and the ghoulrillas roam free. On the outside to the left of the building, Dr. McDermot's grave is found. There is a safe behind the building next to the back wall.
Cito's note is located in the eastern corner, on a box next to Cito's bed.
It is possible to jump onto the hedge surrounding the building from the safe behind the building. There is a space between the hedge and the wall in front of the building next to the gorilla statue where one can fall in, unable to jump out again.