A volcanic crater that visitors can look inside.

A masterpiece of Rationalist architecture in the center of Madrid with lizards on it.

A haven for book enthusiasts across the street from Retiro Park.

A quartet of tiled art pieces adorn the floors of this prestigious art museum.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

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

Paris' linguistic guide to the international language of, yes, love.

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

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

Week-long block party becomes a competition for the best decorated street.

The largest Art Nouveau complex in the world is a Barcelona hospital with a 600-year-long history.

Montreal's colorful subway station shows its support of the local LGBT+ community.

An archway adorned with vulnerable flora and fauna.

The only Leonardo Da Vinci painting in the Western Hemisphere.

The library houses an incredible collection of some of the world's most impressive books and manuscripts.

This coffee shop lies hidden beneath a historic church.

Historic medieval fortified city in southwest France.

An unusual ode to the late Irish playwright, complete with a squiggly bust and coffin-shaped bench.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

The bronze uniforms commemorate the vital role of women during World War II.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

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

The earliest known map to show America, discovered by accident at a Paris bookshop.