This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

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

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

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

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

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

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

Try not to get slimed in Tribeca.

A bizarre house filled with an astounding array of collections.

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

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

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.

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

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

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.

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

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.

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

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

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

Most-visited and most-photographed slot canyon in the American Southwest.