Midewin National Tallgrass Prairie (Former Joliet Arsenal)

At Midewin National Tallgrass Prairie, visitors to the surviving arsenal buildings and grounds report the sound of cars that can't be seen or explained, footsteps echoing through empty structures, and other unexplained noises. This land was the Joliet Arsenal, a massive WWII-era munitions complex built in 1940 across more than 43,000 acres of Will County, where the Kankakee Ordnance Works alone set a national record producing over a billion pounds of TNT with a workforce of 20,000, mostly local residents. Decommissioned after the war, the site became Midewin National Tallgrass Prairie in 1996 — at over 20,000 acres, the largest protected open space in the Chicago area.