Located three miles south of Oregon, Illinois, the Castle Rock State Park is a state recreational facility and natural preserve that is part of the Illinois State Parks system. It is administered by the state through the Illinois Department of Natural Resources.

Castle Rock State Park is located in and around the Rock River Hills region of Illinois and as such features the varying rock topography and geography of the region. Park visitors will be able to view the natural geographic features of the region in its pristine condition along with native natural vegetation and wildlife species.

The Castle Rock State Park currently consists of nearly 2,000 acres of natural preserves and recreational areas. The park was turned into a state park and preserve in 1978.