Northstar Rock is a small area in Red County, San Andreas, located north of Los Santos. The area is named "Northstar Rock" on the map included with the game, however on the in-game map, this area is named North Rock. Swapping the words in the name will yield "Rockstar North," an Easter Egg and a reference to the producer of some of the Grand Theft Auto games.
A little mysterious shack is located up the hill, and just like the shacks to the northwest at The Panopticon, its floors are covered in blood. In the PlayStation 2 version, a random vehicle often spawns in front of the shack.
It is probably based on the real-life Mount Wilson, a mountain north of Los Angeles.