A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

Visit this playground of waterfalls, caves and sinkholes.

A mysterious monument meant to be a guide into "an Age of Reason" was destroyed after an apparent bombing.

These banned cigarette vending machines now sell little pieces of pocket-sized art.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

These beautiful ruins deep in the Pennsylvania woods are thought to have been a ski lodge or a speakeasy, but no one really knows.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

This fast-food outlet is the only space and UFO-themed McDonalds in the world.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

A fiery crater has been burning in the Karakum Desert since 1971.

In 2010, Nicolas Cage purchased two plots in this cemetery using one to construct this strange pyramid mausoleum.

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

The longest hedge maze in the world.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

Historic funicular railway, believed to be the shortest railroad in the world.

An inconspicuous footbridge beloved by San Diego locals.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

Near the former site of numerous witch burnings, this lavish Edinburgh mainstay pays homage to Scotland's brutal history.

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