This massive mushroom has spent centuries eating its way across a huge swath of Oregon.

Atop an active stratovolcano, two lakes separated by a narrow strip of land.

A sprawling cave network created by a lone lava tube.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

This unusual rock looks like a giant, otherworldly mushroom sprouting atop a cave.

Modern megaliths form this work of cosmic, Celtic landscape art.

A labyrinthine underworld of tunnels and caverns hides beneath the city.

A plaque installed underwater marks the fall of a royal family from an imagined parallel universe—part of a globe-spanning art project.

A unique waterfall that some believe attracts the fairfolk.

This ancient holy well is older than much of the city that surrounds it.

A holy well supposedly infused with a saint's spirit flows within this quaint chapel.

In the 9th-century this small spring-fed well became the location of daily mealtime miracles for one Saxon monk.

A ruined castle has more than its fair share of legends and ghost stories.

This historic factory peddles classic toys from the picturesque English county of Devon.

This army of concretions is an unexplained geological phenomenon unlike anything else in the world.

The unpredictability of this pendulum's movements has drawn visitors to this magnificent church for decades.

Cliffs full of fossils at the portal to England's Jurassic Coast.

This Roman quarry once held secret masses and smuggler's contraband and is now home to rare species of bats.

Nature and religion are reunited at this unconventional church in the forest.

"Mock all and sundry things, but leave the saints alone."

Trash escaped from a landfill to fill beaches with all kinds of treasure.

An eccentric inventor's castle home with its own indoor weather system.

A more than 260-year-old crypt built on Boston's oldest English burial ground.

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!