One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

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

A Spanish town built into the cliffs.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

Brussels' favorite peeing boy has a sister.

This modern arts center is built around a gem of late-Baroque architecture.

Three floors of musical instruments coming from all corners of the world and hundreds of years of musical history.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

The "Little Ones," show Portugal in full miniature splendor.

Dead weights honor the dead of Portugal's fishing industry.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

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

This small chapel is built of human bones and decorated with a golden skeleton.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

1,300 chamber pots and their eccentric collector.

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

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

Three bridges and one giant canyon make up this fantastic Spanish settlement.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

This demon atop the Notre-Dame de Paris looks utterly bored.

The celebrated eyesore created by starry-eyed sweethearts.