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

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

The secret city built by the Manhattan Project.

Mile-long cave system near Great Smoky Mountains.

More than five miles of underground passageways.

Railroad came. People came. Railroad left. Town died.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

Visit this playground of waterfalls, caves and sinkholes.

Wild lights and sound effects turn a walk through some caves into an eye-popping 1960s tourist attraction.

Better known as the "Body Farm," this unique research facility has been studying how human bodies break down since the 1980s.

All that's left of the quintessential "cabin in the woods."

Home of an evil witch famous within southern folklore.

Enormous lake at the bottom of a unique cave system.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

The second tallest railway trestle bridge in America.

The remains of a former logging boom town, crumbled away in the forest.

A Seattle oddities shop brimming with Victorian-era gems and antique curio.

A Boeing mechanic and his wife leave a whimsical, stone sculptured garden as their legacy.

Once a year, thousands of naked cyclists flood the streets of a Seattle neighborhood.

The decorations were inspired by an unlikely missing treasure.

In the absence of a Chinese-language newspaper, for years the community posted daily updates on this simple bulletin board.

"The Reptile Man's" very own roadside zoo features an albino alligator.

A giant roadside black bird marks the location of this eclectic local mall.

Protected from the elements, these Native American rock paintings have survived approximately 250 years.