The perfectly named cave drop is the deepest in the continental United States, almost matching the height of Seattle’s Space Needle.

More than five miles of underground passageways.

Visit this playground of waterfalls, caves and sinkholes.

Labor provided by Great Depression-era programs restored these 25,000 acres in Tennessee.

This natural wonder drops 16 stories straight down through rare flora and streaming waterfalls.

All you ever needed or wanted to know about America's favorite whiskey, but not a drop to drink.

One person's lost luggage is another person's treasure.

Bananas are often left for the first monkey America ever recovered alive after being launched into space.

Dramatic river bend surrounds a natural red-rocked pedestal.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

A Saint Nicholas-themed ghost town in the Mojave desert.

Limestone caves with spectacular showcase chambers.

What is the Thing?

This giant steer-skull edifice refuses to die.

This immigrant bridge once spanned the Thames but is now a fixture of an Arizona city.

America's only nuclear missile silo open to the public.

The largest copper mine in Arizona, this enormous open pit emerges from the hills like an alien landscape.

In Tucson a giant metal snake helps pedestrians cross a busy highway.

Sleep where gangsters fell amidst smoke and flame, with nary a bullethole to show for the legendary struggle.

One of the largest, oldest, darkest, quietest motel rooms in the world.

The highest point in Arizona is an oddly snow-topped peak within the otherwise arid state.

This public square capitalized on a single Eagles reference to bring some life back to an Arizona town.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."