Robin:
The Ithaca Gun factory sits atop Gun Hill, a local residential area in Ithaca, New York.  It was closed years ago but the ruins remain behind.  Back when guns were being produced in large numbers, guns were fired off the cliff to make sure they worked.

 

 

The problem is that the factory sat over Ithaca Falls, a large waterfall that contributes to Fall Creek, a long creek that spreads throughout the Ithaca downtown past many residential homes.  The water is toxic in many areas from the gunpowder residue still in the water.