This 19th-century building inadvertently preserved the handprints of its builders within its walls.

In one of America’s oldest mountain ranges, a long-awaited section of a scenic highway is now open to the public.

A recreation of the doomed ocean liner in the middle of the Smoky Mountains.

An abandoned town is hidden in Great Smoky Mountains National Park.

For two weeks every June, fireflies in the Smoky Mountains perform an astonishing light show.

Four hundred granite steps were built into this massive rock by the National Park Service.

Quite simply the largest tree in the world (by volume).

A beautiful geyser under environmental threat.

Steep canyon walls hide a forested oasis in the West Texas desert.

This crumbling stump is all that remains of what was once thought to be the oldest living organism.

A memorial to the unknown and unheralded men and women of the Cold War military and intelligence services.

Paranormal investigators claim this abandoned asylum is the most haunted spot in the eastern U.S.

Mysterious glowing orbs float through the desert night.

A US military accident created the legends behind this Mexican version of the Bermuda Triangle.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

An alien landscape of chalk-rock in the Egyptian desert.

This North Carolina museum is keeping the pinball craze alive, with a little Space Invaders on the side.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

The remains of an idyllic small town built for the film 'Big Fish' still stand around a rundown main street.

All that's left of the quintessential "cabin in the woods."

Cadillac where country's first big star was found dead.

The remnants of an early American attempt at missile defense.

One lonely, modern pyramid has gone from corporate think tank to deserted boondoggle.