A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

A volcanic fissure over two miles long and up to 70 feet deep.

The lush coastal city of Astoria is riddled with forgotten secret sidewalks.

No one knows how this Pacific Northwest spruce tree came to have so many trunks.

Hollowed out cedar log tubs set in an ancient towering forest.

A heavenly experience, right here on Terra Firma.

A beautiful 62-acre Catholic shrine and botanical garden.

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

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

On the Oregon coast there is a natural hole that seems to be draining the sea.

The world's largest man-made underground caverns offer unparalleled underwater wonders.

A jaw-dropping brutalist space church seems to have crash-landed in the middle of America.

A riverside park built around the ruins of a massive dam that collapsed in 1909.

The home where a lovestruck Fitzgerald wrote his first published novel, "This Side of Paradise."

The watery grave of an impractical idea.

For over a century, it was a crucial center of mental health treatment and also the source of many local legends.

1887 era Russian Orthodox church in Minneapolis.

Minnesota's highest point is a scenic vista marked by a plaque and armies of mosquitoes.

Duluth mineral magnates built this charming art deco lodge to be their private clubhouse.

This bright yellow building is packed with sweet treats from all around the world, from chocolate-covered crickets to whoopie pies.