Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

Two geological phenomena in one precarious locale: a towering stone window, and a deep blue void.

This spectacular dome managed to survive after being bombed in World War II, in an event known as the "Miracle of Mosta."

Stone Age solar temple is aligned with the sun on each equinox and solstice.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

A lush oasis full of vibrant plants and striking geometric displays.

One man's remarkable private collection of art from around the world.

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

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

A 16th-century Andalusian palace.

The final resting place of the great navigator, or maybe his brother.

A curious memento mori hangs in the magnificent Cathedral of Segovia.

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

This influential Renaissance-era library was once the haunt of kings and monks.

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

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.

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

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

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

The Guardian of Tallinn.