A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

The 16th-century church has the only stained glass windows that survived the Scottish Reformation intact.

The small alleys in Lübeck's Old Town are a result of medieval urban sprawl.

The bells remain in a shattered heap exactly as they fell when the church was bombed in World War II.

The walls of this medieval church are covered with perfectly preserved frescos, including a pristine example of the Dance of Death.

Dancing skeletal figures pay homage to a medieval mural destroyed during World War II.

The world's fifth tallest waterfall is a spectacular silver chute of water that cuts through the cloud forest in northern Peru.

A long, winding trek rewards you with a gorge so captivating it inspired a painting in the Tate.

This lovely little burbling creek is actually a deadly waterway that has dragged down everyone who ever set foot in it.

The largest cave chamber in Britain—big enough to fit a whole cathedral inside.

This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

The southernmost Anglican cathedral in the world has whale bones standing in its yard.

The barrel-made lookout from Shackleton's final ship is tucked away in the crypt of one of London's oldest churches.

A preserve with 75,000 ancient drawings remains the realm of public – not just scientific – exploration.

The abstract sandstone rock formations at this Algerian national park are rich with prehistoric art.

The oldest working mechanical clock in the world.

This volcanic cave lake is essentially hard proof that Iceland is the most magical place on Earth.

This tumultuous Icelandic lava field looks so alien European researchers want to use it as a stand-in for Mars.

A sulfuric martian landscape that looks far better than it smells.

These ominous lava formations were said to be an entrance to the netherworld so of course they inspired a famous metal band.

Iceland's largest geothermal mud pool is a little bit haunted and a little bit dangerous.

Walk in the footsteps of the gods and straddle two tectonic plates.

Climb right into the heart of this colorful Iceland volcano.

A winding, blood-red tunnel of hardened lava navigable by foot.