An ethereal glowing blue ocean cave in Croatia.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The world's only museum devoted to the wonders of fluorescence.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

A 16th-century horror show built in a lovely Italian garden.

Remnants of a storybook amusement park hidden behind a strip mall.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A striking 12th-century-style castle built on the edge of a cliff.

The name doubles as an appropriate adjective for this small ossuary.

Medieval ruins on a tiny island amid a flooded lake offer romantic respite to lovers seeking privacy.

This 600-year-old home seems to defy physics.

In a small churchyard in Dingolfing, Germany the quaint Schusterkapelle is there to remind you of your imminent mortality.

In 1830, cemetery workers in Cham unearthed a chamber housing thousands of skeletal remains from the 13th century, which can still be viewed today.

When a medieval fire claimed the original St. Stephen’s Cathedral, it sparked a pattern of unquenchable organ building.

This German bone house contains the remains of some 20,000 souls.

These 18th century gardens tell a rocky story of the son of Odysseus.

The history of German architecture is explored across this fairy-scale mini-city.

Tiny castle in the middle of the Rhine made you pay to pass.

The stones of this formerly witch-obsessed castle were used to build a church.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

The world's most delightful not-NOT-religion welcomes visitors to the town of Templin, just like its more stoic peers.