Bingham Canyon Mine

Bingham Canyon Mine 
Bingham Canyon Mine is a copper mine in the Oquirrh Mountain, Utah.
It also man-made hole for mining activities.

Dredging began in 1863 and still continues to this day.
first, mine reached a depth of 1.2 km and a diameter of 4 km.
Currently, the size of the hole has reached a depth of 0.75 miles and 2.5 miles wide.

source: http://unique.shootrun.net