A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

"The most colorful grottoes of the world.

The most visited, and possibly most controversial, museum in Germany.

This short pedestrian span is also known as the "Fairy Walking Bridge" because it looks almost magical.

A complex and beautiful system of rice terraces covers a million acres over the mountains.

This working replica of the 'Friends' coffee shop is more accurate to the show than the set itself.

This Tang Dynasty behemoth is the biggest Buddha in the world.

A tunnel dug through the side of a mountain by hand provides convenient yet death-defying access to a small village in China.

A part of the world's largest marsh seems to be growing bright red Martian grass.

A canvas of crops grow from vibrant red soil in this terraced farmland.

Cliffside houses provide a spectacular view from their perch above the valley.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

Hidden deep in the Guatemalan jungle is a turquoise paradise of natural pools, caves, and waterfalls.

Hidden amid the tropical forest in the Caribbean Sea are the decaying ruins of the Cocaine King's luxurious island party home.

Every equinox this Maya pyramid puts on a spooky ancient light show.

How Quincy, Florida became the richest town per capita due to one man's shrewd business acumen and taste for fizzy drinks.

This historic headstone is said to mark the final resting place of a doubly-dead white witch.

The so-called "world's shortest river" is actually a window into a cave.

A 1950s eccentric's vision of Eden preserved as a hiking trail.

The ruins of this antebellum sugar plantation are the end result of a Seminole attack during the Florida Wars of 1836.

The scuba diving training facility was named for the steam that rises from the cave's chimney.