Big Oaks National Wildlife Refuge Tank Trail Heritage Circuit

These concrete tank roads were built to test military vehicles during World War II, when Jefferson Proving Ground fired over 24 million rounds of ammunition across 55,000 acres. Today, 50-year-old oak trees grow through cracks in the concrete while unexploded ordnance keeps most of this former weapons testing facility permanently off-limits. The accessible portion follows the old perimeter road past concrete bunkers and observation towers, where artillery shells were fired at mock villages and captured enemy equipment was blown to pieces.

Restricted access requires advance reservations through the refuge office, with guided tours only during designated weekends. Standard passenger vehicles can handle the maintained concrete roads, but don’t deviate—unexploded ordnance contamination extends well beyond marked boundaries. Tours operate April through October when wildlife activity peaks. The historical significance is sobering, but the wildlife recovery story is remarkable. Bald eagles, river otters, and elk now thrive where tanks once rolled, making this one of Indiana’s most unique conservation success stories.