Castle Rock State Park is located along the west bank of the Rock River in Ogle County, three miles south of Oregon, on Ill. Rt. 2. The park is centrally located in the Rock River Hills region of Illinois, and its rolling topography is drained by the Rock River. The park is representative of the Rock River Hills area with rock formations, ravines and unique northern plant associations. A sandstone bluff, adjacent to the river, has given the park its name.