This Italian foot path winds through the mountains via 52 individual tunnels.

A beautiful Gilded Age hotel in the White Mountains with surprising diplomatic history.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

A monumental fountain in Rome features a large statue of Moses that has been criticized for centuries.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

The alpine falls where Sherlock Holmes apparently met his demise can actually be visited.

Large Hadron Collider and the Birthplace of World Wide Web.

The World Wide Web was created in this nondescript corridor at CERN.

CERN's beautiful, bending sculpture is a tribute to the spread of knowledge.

This statue of a Hindu cosmic dancer at CERN is a metaphor for modern physics.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

This statue of the great Argentinian car driver is located near a famous curve of the Monaco Grand Prix.

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.

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

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

A curious carving hides on a marble column in the Mosque-Cathedral of Córdoba.

The fragmented remains of a massive public bath connected to the city's water supply.

Once the grandest synagogue in medieval Spain, it now stands as a memorial of the 15th-century Jewish exile.

These abandoned country fairgrounds are filled with replicas of Spanish monuments.

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

Inside this church are the alleged remains of the patron saint of lovers, epileptics, and beekeepers.