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

When ecosystems collide in the arid Southwest.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

The "world's biggest dinosaur" once housed a creationist museum in its abdomen.

The ghostly remains of an accidental sea.

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

Dramatic river bend surrounds a natural red-rocked pedestal.

Most-visited and most-photographed slot canyon in the American Southwest.

America's only nuclear missile silo open to the public.

The world's largest military aircraft cemetery.

One of the world's largest telescopes, stares into the night sky with two huge mirrors.

Rippling sand dunes frozen in the Arizona rock.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

A self-built castle made by a mysterious man.

The rusted remains of a victim of Hurricane Ike.

The tallest sea cliffs on the Southern Hemisphere are a climber's worst nightmare.

A natural gas leak provides a flickering flame beneath a waterfall.

A speakeasy takes on Chicago's drinking culture.

Stunning examples of Russia's 18th-century wooden architecture.

At the "Garage Mahal" in Houston, car culture is about more than just driving.

A canvas of crops grow from vibrant red soil in this terraced farmland.

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

A lovers' beach, tucked below the surface of the island, provides a safe haven for romance.