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

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

San Diego's most historic and haunted home.

Stripes of flowers bloom each spring in a 50 acre rainbow of color.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

The hallucinogenic center of the ancient world.

Tiki luxury on Nob Hill.

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

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A reproduction of earth's many biomes.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

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

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

A battle between nature and architecture in the Cambodian jungle.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

Monasteries on rock pillars, once accessible only by frayed ropes.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

Northern Ireland's Brobdingnagian stepping stones.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

The ghostly remains of an accidental sea.

An artsy hidden staircase leads to breathtaking views of San Francisco.