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

New York's oldest magic store.

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

Try not to get slimed in Tribeca.

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

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

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

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

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

A whimsical art tower at a Bavarian brewery includes a grotto for its mythical beer-brewing dwarves.

The real life town from the Pied Piper of Hamelin has a mechanical puppet show that retells the famous story many times a day.

A former Nazi lookout tower with a magnificent view of the Rhineland.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

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

Dramatic river bend surrounds a natural red-rocked pedestal.

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

A 140-year-old castle with underground caves hidden in San Francisco.

An emerald-green grotto just a short trip from Austin.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

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

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

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