This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

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

Defying all odds, this lonely little tree found a home on a log sticking out of a Canadian lake.

One of the largest barracks of the Austro-Hungarian monarchy's military is now an abandoned ruin.

An eerie, derelict amusement park in Berlin.

The music is over at the Ballhaus Riviera Ballroom, but the ballroom remains in haunting disrepair.

It's always summer at the beach inside this former airship hangar.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.