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

A hidden three-foot-wide house separates these two regal churches.

This massive library holds what was once the largest book collection in the world.

A series of magical limestone formations along the coastline of the country island of Antigua.

A familiar otherworldly creature guards this 12th-century Scottish abbey.

A road runs through the middle of this small Austrian chapel.

More gold than anywhere else, ever.

The world-record holder for the longest bridge stretching continuously over water.

Experience this Iron Age village the way that its original residents would have.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

A painfully obvious spy house sits right across the street from the Russian Embassy.

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

An Industrial Revolution-era public work that purified water using nothing but sand.

A tangible and sobering reminder of an atrocity that took place during a secret war.

The Arctic Archipelago is home to world's largest third order island: an island in a lake on an island in a lake on an island.

See no evil, hear no evil, speak no evil.

Veryovkina Cave is more than 1.3 miles deep—the deepest known in the world.

No one knows how this Pacific Northwest spruce tree came to have so many trunks.

Deceased nuns were placed on stone chairs to decompose, while the surviving nuns prayed near the lifeless bodies.

A uniquely lettered street sign marks the corner where the iconic word game was invented.

For those going through a life transition, a place to leave behind a piece of your former self.

An exercise in patience and imagination, where Mother Earth turned common stuff into precious hidden treasures.

Descend 2,030 years into the past in an ancient tunnel built to support Jerusalem's most famous wall.