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

Mile-long cave system near Great Smoky Mountains.

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

More than five miles of underground passageways.

Visit this playground of waterfalls, caves and sinkholes.

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

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

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

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

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.

One of corporate America's best-kept secrets is also one of the most publicly displayed.

One-of-a-kind museum inside the first Boeing 747-400 ever made.

A colorful square marks the heart of the city's LGBTQ community.

The largest cemetery in the American Southeast is a hidden gem near the heart of Atlanta.

The beauty of urban decay, hiding some dark secrets.

An overlooked monument to the celebrity gangster who helped put the sin in Sin City.

A collection of haunted objects and macabre oddities under one roof.

A blacklight mini-golf fever dream pays tribute to the iconic rock band.

Originally built as a promotional giveaway, this suburban house was designed to be an IRL version of the Simpson home.

A new kind of theme park for adults off the Las Vegas Strip.

Thousands of artifacts relating to human sexuality, including the world's largest sex bike.

The bullet-riddled wall from the St. Valentine's Day Massacre, bloodstains enhanced for your viewing pleasure.

James Turrell's total color immersion art installation, hidden on the top floor of a luxury handbag shop.