An American ghost town hides along a side street in Scotland's capital.

A beautiful Greco-Roman structure houses a well once believed to have healing powers.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

A steampunk-styled three-floor factory churning out art, activism, and electronic beats.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

One of the famous Czech artist's lesser-known Prague installations appears to be a glowing fetus affixed to a drainpipe.

This doorless 20th-century elevator doesn't stop or slow down.

The last municipal pneumatic post system in the world was in operation for over 100 years, and may run again.

Site of the first radio and telephone broadcasting companies in Copenhagen.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

Visitors are treated to a stained glass kaleidoscope interior inside this work of art.

This secret collection of the strange and occult was rediscovered in a forgotten room of an old house.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

On the Oregon coast there is a natural hole that seems to be draining the sea.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

A beautifully eclectic mix of architectural styles.

The final resting place of the "father of special effects."

France's most famous cemetery, with some of its most curious tombs.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

Abandoned railway line circling the city of Paris.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.