A beautiful but toxic fountain of mercury.

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.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

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

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

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

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

This luxury shopping lane has been protected by its own tiny police force for over a century.

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

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

A public urinal so pretty, it was declared a national monument.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This bridge was constructed from the rubble of the infamous Bastille.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The footprint of a frustrated devil in Munich's Cathedral.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.