Sanctum is a noun that refers to a private place from which most people are excluded. 

The Latin word sanctus (SONG toose) means ‘holy.’ Our word of the day emerged in the late 16th century, taking with it a religious connotation. A sanctum is not necessarily holy, but it is often treated as if it were. 

My dad’s study was a sanctum around our house and he treated it like a shrine. No one was allowed to enter except him.