Iceland's largest geothermal mud pool is a little bit haunted and a little bit dangerous.

Walk in the footsteps of the gods and straddle two tectonic plates.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

The world's largest wooden structure.

Walk into an underground archeological dig, the site of the Roman Forum that was once the center of Valencia.

This amazing example of Valencian Art Nouveau looks more like a cathedral than a public market.

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

An early 20th-century bullring converted into a modern shopping center.

One of Antoni Gaudí’s earliest buildings, built between 1886 and 1890 for the industrialist Eusebi Güell.

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.

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

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

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

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

This emotive sculpture was originally created for the 1878 World's Fair.

A beautiful Victorian statue shows France's enduring love of the rhinoceros.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

This recessed garden protects thousands of mountain plants by creating its own microclimates.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

The video game-themed street art first popped up in the French city.

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

A surrealist timepiece by the artist of melting clocks.