An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

This belfry is all that remains of the town that was buried by a violent volcano eruption.

A melting pot of Asian-Pacific art features one symbolic sculpture from each of 20 different nations.

The wreckage still sits at the exact spot the plane crash-landed in 1945, carrying 1,000 pounds of explosives.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

The oldest surviving glass furnace cone in Western Europe.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.

This historic little railroad runs through some of the most beautiful scenery in Germany.

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

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

This ruin in a suburban park may be the place where Shakespeare's "A Midsummer Night's Dream" was first performed.

This Roman amphitheater is said to be King Arthur's legendary Round Table.

This macabre monument atop an ancient well gives a nod to a brutal episode in Scottish clan history.

England’s ancient oak tree has such an impressive girth, people have been hosting parties within the hollow trunk for centuries.

This wondrous waterfall rushing down a green-covered mountain wasn't discovered until 2010.

A little-visited waterfall in an otherworldly landscape.

A locomotive that was captured as a prisoner of war is now recognized as a WWII memorial.

A unique beach made of a myriad of multi-sized pebbles.

Bohol's mysterious brown hills.

A patch of Philippines forest devoted to saving the lives of an emotionally sensitive species of googly-eyed primates.

The wooden telephone box hidden away in London's Piccadilly was the original prototype of the iconic kiosk.

The abandoned summer estate of the former Greek Royal Family.

The only Florida state park with publicly accessible caves.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.