Elevated freight railway turned wildly successful urban park.

A crumbling hospital from the 1850s on Roosevelt Island.

When a supermarket opened up shop within a medieval building it became protected by UNESCO on a technicality.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Five candy-colored villages on the Italian Riviera.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

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

This Gothic church houses ornate royal tombs and a magnificent gilded altarpiece.

These three pillboxes still remain as a witness of the Spanish Civil War in a park of Madrid.

The most elaborate of 12 medieval arched doorways to the old city of Burgos.

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

This remarkable museum sprung from one of the most important prehistoric archaeological sites in the world.

A somewhat mysterious biomedical museum housed inside a Spanish university.

This line of 12 tower mills described in the story of Don Quixote is among the most iconic landscapes in Spain.

Giant topiary dog once played a role in a terrorist bomb plot.

This sweet-toothed bear searching for snacks has been a symbol of Madrid for decades.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

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

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

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

Revel in the Victorian splendor of the world's oldest eating establishment inside a museum.

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.