Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

Twice a year, visitors can tour the desolate site that birthed the Atomic Age.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The world's tallest church tower reveals a spectacular view to anyone up to the task of climbing the daunting staircase.

Remants of foundations, streets, and streetcar tracks inhabit the cliffs where a landslide occurred in 1929.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

Splashes of blue in an otherwise monotonous lunar landscape.

One of the deepest indoor swimming pools in the world.

Large pioneer village showcasing life during boom times.

Costumed elves and mountain bikers co-exist peacefully at this abandoned Christmas-themed adventure park.

On the coast of Sardinia, a once-great mining village is finding new life as a coastal resort town.

A fantastic castle rumored to be the birthplace of King Arthur.

An arresting arch punched straight through a mountain provides one of the most scenic spots, and challenging climbs, on the planet.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

Crumbling remnants of what was once a booming town full of silver.

World War II-era Nazi compound nestled in the Santa Monica hills.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

Renaissance villa and gardens complete with a tormented colossus.

An enormous concrete structure built over a nuclear crater.

Remote, volcanic island that Darwin, Hooker, and the Royal Navy shaped into a thriving, artificial ecosystem.

This 14th century castle withstood years of battle but is now sliding off the hills into the Danube.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Millions of glowing microscopic organisms light up the waters of this luminous lagoon.