Take a dip beneath the stalactites in this amazing cenote.

Found down a long dirt road, a sacred Mexican cenote and 18th-century hacienda remain hidden.

Three sinkholes filled with warm, crystal-clear water reached by a horse-driven cart on an old train track through the jungle.

This massive subterranean fissure is known as the "underground Grand Canyon."

A reportedly haunted parking structure with alleged links to Jack The Ripper.

The oldest hotel in the world has been operated by the same family for over 1,300 years, even catering to samurai.

A rainbow-colored house promotes LGBTQ rights across the street from the Westboro Baptist Church.

The scene of the United Kingdom's most famous UFO incident, dubbed the "British Roswell."

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

The world is full of swimming holes, but few compare to Samoa’s idyllic To Sua ocean trench.

A perfectly circular lake is formed by the crater of an ancient underwater volcano.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

The gathering point of an old Melbourne swimming club was site of a historic, world-record dive in 1918.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Beautiful Victorian buildings from L.A.'s forgotten architectural past.

Rare collectibles from automated musical instruments to 250 unique automobiles.

A common entry point to the Griffith Observatory trail holds its own wonders.

This peaceful oasis appears dreamy, but it's also the site of a nightmarish legend.

In 1329, Christine Carpenter entered this small stone cell in the hopes of becoming a living saint.

This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

This letter written by Queen Elizabeth II in 1986 won't be opened until 2085.

The first woman in America to receive a medical degree.

Over thousands of years, this slot canyon was carved out of the bed of an ancient lake.

A memorial commemorating the only Scottish police investigation into an extraterrestrial incident.