A farmer in Illinois was left scratching his head when he discovered a mysterious tunnel on his property that historians say likely dates back to the 19th century. According to a local media report, Gary Machens stumbled upon the puzzling passage when he noticed that the sidewalk outside his home in the city of Alton was inexplicably sloping and set about trying to fix the problem. As he was excavating the area and adjusting the rock wall which sat beneath the sunken pavement, the bewildered farmer spotted an opening that led to a rather lengthy brick tunnel. After checking with historians in the city, Machens was told that the passage was likely constructed around 1840, though its purpose is anyone's guess.
More on this story at the Coast to Coast AM website.