A walk through the historic city center, under the streets of Seattle.

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

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

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.

The sign at the garden gate reads: "These Plants Can Kill."

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Abandoned railway line circling the city of Paris.

New York's oldest magic store.

Medicinal spa created with the discharge from a geothermal energy plant.

Dramatic river bend surrounds a natural red-rocked pedestal.

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.

On this wooded path, a stained-glass window creates a spellbinding forest cathedral.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

On the Oregon coast there is a natural hole that seems to be draining the sea.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

World's first "penitentiary," meant to be humane, drove men insane.

The sound of swaying stalks in this stunning grove has been named a governmentally recognized sound.

An exquisite tunnel of cascading flowers.

This iconic L.A. bookshop is housed in an abandoned bank—both symbolic and chic.