Buffalo Rock State Park is located on a bluff which was once an island in the Illinois River. Now standing majestically on the north bank, this promontory affords a magnificent sweeping view of the Illinois River. Located approximately three miles west of Ottawa in LaSalle County, this 298 acre park has long been a favorite picnic area, as well as a nature lovers delight. The area of Buffalo Rock was the home of the Illinois Indians when Louis Jolliet, the French explorer, and the Jesuit missionary priest Father Jacques Marquette made their trip up the Illinois River in 1673. Later the Illinois Tribe was virtually annihilated in protracted warfare with the aggressive Iroquois.
It's a nice park, not a ton of hiking. Some nice overlooks of the Illinois River. There are Effigy Mounds to look at along a flat hike. These were made in the 20th century. Also, there is a live buffalo to see. If you're a cyclist, you could ride up from the Illinois and Michigan Canal Trail.