Illinois is full of natural wonders and prehistoric monuments, some of the most fascinating examples are found in our caves and mounds.

Head down to Cave-In-Rock State Park in southern Illinois, where a massive riverside cave carved into the limestone cliffs has captivated visitors for centuries. Once rumored to be a hideout for river pirates, but don’t let that dissuade you from visiting, this site now offers a scenic and safe peek into the state’s rugged past.

A bit farther north, Illinois Caverns State Natural Area near Waterloo is one of the few public wild caves in the Midwest. With its underground streams, mineral formations and cool year-round temps, it’s a true adventure for nature lovers and geology buffs alike.

Above ground, Illinois is home to some of the most important Native American archaeological sites in the country. At Cahokia Mounds, just outside of St. Louis, you’ll find the remnants of a massive city that once rivaled London in size. It’s a powerful reminder of the Mississippian culture that thrived here long before European settlers arrived.

For a more intimate experience, Dickson Mounds offers insight into Native life along the Illinois River. Its museum and trails overlook the valley, once home to generations of Indigenous communities.

From underground to prehistorical heights, these sites offer an immersive way to connect with Illinois's natural and cultural history.