A spectacular cave and a beguiling lake.

Ancient Greek oracle of the dead.

Monasteries on rock pillars, once accessible only by frayed ropes.

The solemn exterior conceals an opulent interior of this 17th century church.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

The final resting place for the remains of 143 Habsburg royalty.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

A little church on a tiny island looks like something from a fairy tale.

This Sumatran root bridge took almost 30 years to knit itself together.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

Submerged trees jut ghost-like out of an idyllic turquoise mountain lake.

The lovely lake that was naturally dammed, then naturally destroyed, then unnaturally saved.

This disused church, left to the elements of the Arctic Circle's forests is open for exploration.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

What was to be the world's most secure Cold War document vault ended up as just a few shallow caves.

The abandoned village of Skarð aptly illustrates the idiom "Don't put all your eggs in one basket."

This remote island village was in danger of depopulating completely until a tunnel was built to connect it to the rest of the world .

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

On Keriri/Hammond Island, a marker shares the story of an imprisoned woman and the island she saved and that eventually saved her—in the fictional world of Kcymaerxthaere.

This odd 1930s shop remains stranded in time and shrouded in mystery.

The UFO capital of Australia is the outback’s answer to Roswell.

This abandoned railroad tunnel is now home to a micro-colony of bats and a ghost train.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

An incredible garden taking over the interior of a massive sinkhole.