If you are going to pay to see a big hole in the ground, then the
Kennecott Utah Copper's Bingham Canyon Mine is a good place to start. It is the world's largest man-made excavation (can be seen from space). Since open-pit mining began in 1903, enough material has been removed to create a pit that is more than three quarters of a mile deep and two-and-a-half miles wide. Still in operation, this massive mine has yielded more than 19 million tons of copper as well as vast quantities of gold, silver and molybdenum. Click on photos to enlarge.
I was going to put a set of these on my UTV until I saw they were $25,000 per tire...