The world's second-largest sundial, made entirely out of stone.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

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

Roman ruins top white travertine terraces formed by ancient hot springs.

This sinkhole in the Arizona desert is filled with carbonated, arsenic-rich water

Space-age monument to an early 20th-century uprising.

The Grand Canyon’s original airport, which once welcomed pilots like Amelia Earhart and Charles Lindbergh, lies abandoned.

This massive underground salt mine now holds a sci-fi theme park in its depths.

A honeycomb-like structure of interlocking shelves creates a beehive of books.

This groundbreaking 16th-century map is known as "America's birth certificate."

The oldest stone house in Paris was built by its most famous alchemist.

The ship that got left behind.

Despite what a Thai tourism board might want you to think, this white-sand beach is in fact located on a Scottish island.

Final resting place of Antarctic explorer Ernest Shackleton.

This otherwise innocuous bodega was once the headquarters of the most feared assassin's guild in American history.

Established over a thousand years ago, this family-run teahouse continues to serve skewers of sweet rice cake to this day.

A bizarre house filled with an astounding array of collections.

Two men built this castle on the Florida coast as an artistic “landscape sculpture.”

Every day is like Christmas on this street where the traditional Neapolitan nativity scene comes to life.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

This incredible collection of vintage pinball machines can be played at 25 cents a pop.

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

One of America’s oldest and spookiest hotels, thanks to the residency of ghosts, dead presidents, and Alfred Hitchcock.

The hallucinogenic center of the ancient world.