Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

A Cuban artist reclaimed his impoverished neighborhood as a dreamy folk art kingdom.

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

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

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

These small, triangular, colorful houses are a staple of Madeira Island.

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.

A lush indoor jungle fills this bustling Madrid transportation hub.

An ancient Egyptian temple in the middle of Madrid, Spain.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Romania's triumphal arch looks out over Bucharest.

This once-derelict building is now one of the most beautiful bookstores in the world.

There's a mini version of Iguazu Falls hidden in the Balkans, and it's got a rope swing.

Bridge that died in war and was resurected.

The first mosque in the world to receive electricity.

The place where World War I began.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

Banksy's image of a naked man dangling from the window of a sex health clinic.

The Bristol Camera Obscura housed in an ancient windmill.

Op-art architecture designed for happiness.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

The final resting place for the remains of 143 Habsburg royalty.