The Gravity Falls History Museum is a museum detailing the history of the town of Gravity Falls. It shows various pieces from all throughout its history, and has a large part in Pioneer Day.
During Pioneer Day, Dipper and Mabel follow a map hidden inside of the book 3 to the museum, hoping to find who the true founder of Gravity Falls was. There, they find a strange piece of abstract art that is the same shape as a picture on the map. Not knowing what to make of it, Mabel lays on the bench in front of it upside down. She then realizes that the piece is actually a statue of an angel pointing upside down, pointing towards the town's cemetery.