This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Madrid's last horchata kiosk is a blue-and-white beacon of refreshment.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

For decades, Puerta del Sol has been illuminated by a giant, guitar-wielding bottle of sherry.

Secret refuge and museum of the Duke of Florence.

More than 450 years ago, an Italian nun became the first woman to paint the iconic subject.

The mummified relic of St. Antoninus.

Watch the newest land on the planet form before your eyes.

This black shoreline is made up of exploded lava particles.

Earth's tallest volcano is sacred to Native Hawaiians, and home to a dozen world-class observatories.

This unusual lava tube spouts seawater during high surf.

A series of waterfalls and pools that flow through the 'Ohe'o Gulch and into the ocean.

Take shelter from Hawai'i's tropical heat under the massive canopy of largest Banyan tree on the island.

A Hawaiian stairway to heaven—that you can't climb.

This former luxury resort in Kaua'i is now an abandoned relic.

This blowhole is supposedly caused by a trapped monster.

An authentic replica of an Asian temple and garden hidden amongst the natural beauty of Hawai'i.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

The oldest operating pharmacy in the world features 800-year-old recipes.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

The only museum with its curator—and her pets—buried inside.