Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

Rare recess caves fill this unbelievably beautiful Ohio park.

Spend the night in this formerly abandoned traditional Scottish village.

This spectacular track has run continuously since 1882.

The humble field where the first Major League Baseball game was played.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

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

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

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

The eerie ruins of a remote abandoned hamlet said to be founded by the survivors of a shipwreck.

In the woods of New Jersey lie the ruins of a munitions village abandoned after World War I and the remnants of a 1920s wooden racetrack.

The remains of an old sawmill, gristmill and the surrounding industry dating back to the 18th century.

Whimsical artist house in the New Jersey woods.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

This massive boulder is either a unique rock formation created by glacial melt or a magic energy vortex.

This tiny New Jersey village has lived many lives but seems determined to remain a ghost town.

The underground sanctuary of a mysterious ancient Roman religious cult contains an exquisite traditional fresco.

Once thought to be the oldest living tree in the world, Methuselah was germinated before the Egyptian pyramids were built.

The hidden lair of an alchemist rediscovered in a 2002 flood.

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

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

An exquisite tunnel of cascading flowers.