Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

The only urban monument in the world designed by the great surrealist painter Salvador Dalí.

Commonly acknowledged as the only public monument to the Devil himself.

A lush indoor jungle fills this bustling Madrid transportation hub.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

"Portugal's Stonehenge" is made up of nut-like stones aligned with the heavens.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

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

Ancient catacombs form the foundation for this Rococo orgy of a church.

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

A statue honors the children who fought Nazis in Poland.

A striking public sculpture representing the period of martial law in Communist Poland.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

This man-made mound monument was built out of soil from all across the Polish empire.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

A line of disused military bunkers built to defend against Nazi invasion lies hidden on the outskirts of the city.

A unique hotel for the artistic soul.

This one-time health resort was used by aristocrats around the world.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.