Rib Mountain (also known as Rib Hill) is a glacially-eroded monadnock in central Wisconsin, located in the Town of Rib Mountain in Marathon County. Composed of quartzite covered with a softer syenite sheath, it was intruded about 1.5 billion years ago. Rib Mountain is at , near Wausau on the west side of the Wisconsin River, just west of Interstate 39 and just south of Highway 29. Local legend states that the 'ribs' in Rib Mountain come from the fact that it is the burial site of Paul Bunyan. Furthermore, nearby Mosinee Hill is said to be the grave of Babe the Blue Ox.