These fantastically named natural pools look like something out of a Scottish myth.

Treehouse motel and treehouse-building school.

They call this long foot bridge a swinging bridge, but really it's the bouncing you have to watch out for.

Bad farming practices caused this unnatural natural wonder.

"X" marks the spot of an echo chamber in the middle of a plaza.

This quirky curiosity shop takes its cues from the world's bazaars.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

One man's ambition created this psychedelic log home.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

An underwater city for the dead.

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

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

Natural time capsule containing an alien ecosystem.

These azure waters were thought to lead to the Mayan Underworld.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

Northern Ireland's Brobdingnagian stepping stones.

Beyond being incredibly fun, not much can be said about the Hole with certitude.

The first declared National Monument in the United States.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.