Huge masonic hall in Philadelphia with lavishly themed rooms.

Where America's first doomsday cult awaited the end of the world.

A legendary speakeasy bookstore returns from the brink.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

A religious-themed park filled with folk art to bring biblical stories to life that fell into disrepair and now being restored.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

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

This lab's maddening silence is good for business but bad for sanity.

Mysterious rocks that ring musically when struck.

A layered tribute to the work of mosaicist Isaiah Zagar.

A toxic ghost town sitting atop a massive coal fire.

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

A bizarre house filled with an astounding array of collections.

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

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.