A naturally beautiful, seemingly bottomless deep blue spring.

A medieval bridge stretches over a sulfur-rich river that leads to year-round natural hot springs.

Local lore says two enemy dragons live within these breathtaking mountain lakes.

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

Ancient Greek oracle of the dead.

A secret door leads to this cozy dive that sells only “milk.”

This 13th-century monastery chiseled into the side of a mountain is equipped with a bridge that can be lifted to protect against raids.

This 24-acre park offers a place for meditation in the midst of Sedona's iconic red rocks.

This hermitage spanning an Italian river gorge draws pilgrims hoping to heal ailments like arthritis and migraines.

There are ongoing efforts to preserve this village, the best known work of Egyptian architect Hasan Fathy.

This dreamy street will transport you to wintertime in Victorian England.

This hospital once pioneered the use of electroencephalograms, but fell into maltreatment, abuse, and eventual abandonment.

After years of slow decline, a derelict Gothic castle is now being restored to life.

The decaying ruins of Wales' first asylum for the mentally ill.

Picturesque ruins once held off mighty armies.

Also known as "Leicester's Folly," this almost cathedral was left unfinished and in ruins.

This abandoned asylum in Wales might look haunted, but it's still beautiful.

Western Europe's only representation of a Roman goddess still in its original location sits in an unassuming park.

A rare wooden coffin set vertically into the Gothic arch of an ruined church.

The second-longest pier in the U.K. stretches a whole kilometer into the Irish Sea.

Mysteriously stacked storefront paths give this medieval British town an iconic style like none other.

At the United Kingdom's only residential library you can sleep among the books.

Chester Cathedral is home to a unique painting crafted on a canvas of cobwebs.

A mysterious demonic figure peers down from its perch within the gorgeous Chester Cathedral.