Sentinel Hill is a location in the fictional town of Dunwich, Massachusetts, created by H. P. Lovecraft in his story "The Dunwich Horror."
The hill, located near the Whateley farm, features in the story as the site of the Whateley family's May Eve and Halloween rituals. At the climax of the story, it's where Henry Armitage confronts the Dunwich Horror--fulfilling Old Whateley's prediction that "yew folks’ll hear a child o’ Lavinny’s a-callin’ its father’s name on the top o’ Sentinel Hill!”
There is a "sizeable table-like rock" atop Sentinel Hill that serves as a ritual altar. There are also "deposits of skulls and bones," thought by Dunwich residents to be the buried remains of the Pocumtuck Indians, though ethnologists maintain they are Caucasian in origin.
There may also be one of the "great rings of rough-hewn stone columns" found on Dunwich hilltops. These structures are generally believed to be the remnants of the Native American cult which practiced religious rites on the mound before the colonisation of Dunwich, although some think that they predate even this.
The elder Whateley was rumored to have performed a profane ritual atop Sentinel Hill before the birth of his daughter's children Wilbur and Yog.