Before its closure in 2002, this South Dakota mine was the largest and deepest gold mine in Western Hemisphere.

This former mining town was named the most toxic town in America.

A remarkably opulent mansion with a tragic history.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

Less a museum than a bizarre fantasy world created by artists and engineers.

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.