Once upon a time these giant concrete tanks were used by local fishermen to clean their wild-caught mussels.

Once the largest unsupported dome in the world, beating out the Pantheon and St Peters in Rome.

One of the shortest streets in York has an especially odd name.

At 22 feet tall, these Bronze Age monoliths are some of the tallest standing stones in the United Kingdom.

The last fully working Victorian Turkish bath in England.

Where Agatha Christie mysteriously disappeared in 1926.

Touching the iron railings of Tarragona's balcony to the Mediterranean is said to bring good luck.

This Roman arena once played host to bloody gladiatorial battles.

An accidental trick of light casts the perfect shadow of a pilgrim of the Camino de Santiago against the cathedral wall.

Two towns are linked by an engineering marvel masquerading as a boring suspension bridge.

Catalonia Tradition: Beating the hollow Christmas log until it defecates in your fireplace.

Remarkably intact Roman stone fortifications have encircled this Spanish city for centuries.

Vibrant street art created with mixed media.

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

On La Gomera, "Silbadors" communicate in a 4,000-word language of whistles.

Holy Grotto of Montserrat Monastery holds one of Europe's mysterious black Madonnas.

The oldest Roman lighthouse still in use.

Of the many chalices in the running for the Holy Grail, this one in Valencia Cathedral sure looks the part.

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

Hidden behind a wall, Spanish nuns distribute their signature sweets on a revolving tray.

Stunning Roman aqueduct used for 1900 years and still standing.

Giant eggs, walls of bread, and nightmare surreality mark the largest collection of works by Salvador Dalí.

Natural stone arches form a walkable "cathedral" at low tide, then disappear entirely when the water returns.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.