The abandoned ruins of a beautiful medieval castle just outside Barcelona.

This whimsical winery by Antoni Gaudí looks ripped from the pages of a fairytale.

A 19th-century funicular railway shuttles visitors up this surprising sea cliff to one of the world's largest camera obscuras.

This peculiar Italian elevator runs both horizontally and vertically.

This long unused shot tower on the Mississippi remains a point of pride for a small city in Iowa.

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

Outlaws, hot springs, and tragedy have all left their mark on this ancient road in the Icelandic highlands.

Near Birmingham, England three and a half miles of top-secret tunnels housed a World War II “shadow factory” and a Cold War nuclear bunker.

A perilous medieval road leading right into the sea.

A spherical "micro-nation" in the heart of Vienna.

This giant dish located in a sheep paddock was the primary receiver of Apollo 11 TV transmissions.

A stray meteor left this picturesque hole in the Australian outback.

One man's artistic vision is a small town government's legal battle.

These Australian rock formations look like Martian beehives that have grown up out of the landscape.

Critics argue this boab tree has been mislabeled for the sake of dark tourism, undermining its spiritual significance.

This pair of Australian "waterfalls" appear to be falling straight across the land.

The remains of this early 20th century refinery loom on a mountainside like a graffiti-covered fortress.

Eerie ruins of an abandoned medieval fishing village crumble atop an unforgiving stretch of earth.

Gargoyle head that brings good luck.

An ancient knight and a symbol of the city's freedom.

A wunderkammer of gold and silver reliquaries and ancient saintly bones.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

A century-old shot ball factory tower is open to the public once a year.

A maze of underground tunnels beneath one of the most beautiful forts in Serbia.