A historic observatory now an astronomy museum beautifully situated at the moat of the Middle Age city centre.

The world's first interactive human body museum also serves as a chair for a giant orange man.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

This giant wooden treehouse within a sprawling garden has its own eatery.

This pirate-broadcasting-tower-turned-restaurant played a rebellious role in the history of Dutch television.

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

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

This former tuberculosis research hospital endeavored to cure the dreaded disease with fresh air and positive attitudes.

The world's longest known cave system.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

A beautiful geyser under environmental threat.

Where manatees are the snowbird vacationers in these balmy Florida springs.

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

The seamy, underground secrets of Portland's criminal past.

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

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

These massive concrete balls were used to mine gold in Virginia.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

This sprawling farm was once a Cold War-era hideaway for the nation's top diplomats.

Hear, smell, see, taste, and touch history at this immersive Civil War hospital.

This museum explores the grim reality of life in the earliest British colonies in America.

This maze-like slot canyon is a unique gem within an already fascinating geological area.

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.

A grassroots community effort in the 1970s led to the creation of this beautiful garden full of delightfully whimsical exhibits.