Jellystone Park™ of Chicago, a Sun RV Resort in Millbrook, Illinois, offers pet-friendly tent campsites, RV sites and vacation rentals. Guests enjoy amenities like two heated swimming pools, a kiddie pool, dog park, mini-golf course, Gaga ball, volleyball, basketball and planned activities for all ages. Close to the Fox River, Millbrook North and Sound Nature Preserves and Buffalo Rock State Park.