Railways may have forged this quintet of lovely tunnels, but now they are open to hikers.

One of Canada's most incredible rare book collections holds hundreds of thousands of gorgeous tomes that the general public can touch.

A book collector's dream, this Toronto bookstore has the world's first "Biblio-Mat," a random book vending machine.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.

A beautiful geyser under environmental threat.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

This historic stone bridge has an entire neighborhood clinging to its sides.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

An intricate and amazing house built by architect Karl Junker.

A striking 12th-century-style castle built on the edge of a cliff.

Skeletons dressed in extravagant 18th century royal costumes cavort in the aisles of this German basilica.

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

Ruins of a German Castle on top of a towering stone pillar.

The fairy tale castle of the "fairy-tale king."

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

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This massive subterranean fissure is known as the "underground Grand Canyon."

Iron Age grave stones and Viking burials, a short drive from Gothenburg.

This encrypted monolith protected a secret of Norse mythology by hiding in a church wall for over a millennium.

The world's oldest individual clonal tree looks like a wimp despite standing tall for 9,550 years.

A little-visited waterfall in an otherworldly landscape.

According to legend, this boat-shaped henge is built over the grave of a mythic king.