Man finds mysterious 19th-century tunnel under his Illinois home where three mayors have also lived
Gary Machens, from Alton, Illinois, first discovered the mysterious tunnel when he noticed his sidewalk was starting to slope
Machens was already familiar with the history of the home, which dates back to the 1890s
The tunnel was believed to have been created in the 1840s
He believes that the tunnel opening got covered in 1895 when the brick street was laid down