Enormous lake at the bottom of a unique cave system.

A 200-year-old bar in the historic French Quarter refuses to give up its place in history, nor its role in securing ours.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

A toxic ghost town sitting atop a massive coal fire.

A giant Troll lurks under one of Seattle's oldest bridges.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

Elevated freight railway turned wildly successful urban park.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

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

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

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

The only structure left with direct ties to the Salem witchcraft trials of 1692.

A bizarre house filled with an astounding array of collections.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

Dramatic river bend surrounds a natural red-rocked pedestal.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

An enormous, inside-out glass globe built in 1935.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.