Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

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

A terrific purveyor of natural history objects and curios.

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

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

A fiery crater has been burning in the Karakum Desert since 1971.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

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

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

A layered tribute to the work of mosaicist Isaiah Zagar.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

Neither bomb blasts nor heartbeats escape the giant ears of this super sci-fi Arctic outpost.

This museum started as a collection of Manhattan Projects and continues to add exhibits as they are declassified.

One of the oldest log cabins in America is one of the last of its kind this historic Swedish dwelling remains a piece of living history.

The headquarters of the Fraternitas Rosae Crucis, complete with Rosicrucian pyramids, all in the Pennsylvania woods.

An abandoned stretch of highway, deteriorating next to the operational one.

Dedicated to the art and science of glass in equal measure, this space is as much laboratory as museum.

This lush forest valley was once mined for lumber to the extent that it was once nicknamed "The Pennsylvania Desert."

The longest living non-clonal organisms on Earth.

Dig for your own trilobites in this goldmine of invertebrates.

An arsenic-filled pool in the Grand Canyon takes on the appearance of a giant, overflowing pumpkin.

Twenty-seven massive radio antennas on the high plains of New Mexico search for life on other planets.

One of the largest, oldest, darkest, quietest motel rooms in the world.