Scotland's oldest medieval bridge is also among the last reminders of early medieval Aberdeen.

The ruins of this gorgeous clifftop castle look like something from a fantasy novel.

Scotland's only funicular railway is also the United Kingdom's highest.

These ruins witnessed the final gathering of the failed Jacobite Rebellion.

Where the sleeping monsters of Scotland's oil industry are left to rust.

The remains of Alfred Nobel's first nitroglycerine factory can still be found on the shores of a Swedish bay.

Constantly maintained, this organ is playing a six-century long composition by John Cage.

"The most colorful grottoes of the world.

The largest brick bridge in the world.

Oberweissbacher Bergbahn - a broad-gauged cable car capable transfering railcars.

This German "living museum" is maybe a bit too immersive.

Money made from smuggling sugar helped create this wondrous rock maze in honor of the Prussian Queen Louise.

Most often copied TV Tower in the world.

The hidden lair of an alchemist rediscovered in a 2002 flood.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A Jenga-style cylindrical tower of books that appears to go on forever.

Macabre astrological automaton clock dating to the late 1400s.

What looks like a suicide in progress is actually a statue of Sigmund Freud.

The tunnel's elegant proportions keep you snug with no claustrophobia freak-out.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

This artificial cave looks like something out of a fairytale.

Buried five stories underground, this Soviet bunker is packed with gas masks and Cold War paraphernalia.

This former quarry is now a picturesque gorge that hides a sunken lake.