Cathedral carved out of salt, located a mile below the earth's surface.

This picturesque mansion has gone from opulent ruin to nature museum.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

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

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

This semi-secret storybook hedge maze is also the oldest garden in the city.

A unique exhibit lets blind people experience famous works of art and architecture with their hands.

Earth's rocky history has rarely glittered so brightly as it does in this Spanish museum.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

A 16th-century Andalusian palace.

The world's largest wooden structure.

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

The Flatiron Building's storied West Coast cousin is a lot more into religion.

A massive ultra-modern church presents a science-fiction view of Catholicism's inclusive future.

International delicatessen has been owned and operated by the same family for more than 110 years.

A crumbling Beaux Arts monument to the Bay Area's age of rail.

Bonsai garden in Oakland is curated by the first non-Japanese female bonsai master in the United States.

Julia Morgan's Moorish-Gothic labyrinth of fountains, trees, natural light and Oakland's notable dead.

Four miles of pipelines form the model of still-functioning retro-tech efficiency.

This odd California folly seems like it was almost designed to accumulate urban legends.

A hidden world of exotic succulents and cacti.

The ruins of an ancient stadium that hosted gripping chariot and horse races.