The world's most active stratovolcano is almost always erupting.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

This museum is rotten with a century of wax medical deformities.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

Secret refuge and museum of the Duke of Florence.

Romans built the world's tallest artificial waterfall in 271 BC.

One of the world’s smallest bars, just 13 square feet, is brimming with speakeasy flair.

Venice's island of the dead.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

The plague quarantine island home to the alleged "Vampire of Venice."

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

Pilgrimage site for star-crossed lovers.

The abandoned "Ghost Mansion" was left to decay in the mountains of Northern Italy.

Abandoned medieval hill town.

Jesus' footprints and the first catacombs in the world.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

Geothermal waterfalls in Tuscany.

Outstanding collection of 19th century medical instruments includes a life-size figure cast from as many as 200 cadavers.

A former mental hospital founded in the 1930s by a eugenicist who advocated for the forced sterilization of patients.

The largest cemetery in the American Southeast is a hidden gem near the heart of Atlanta.

Lines from a walking song are etched into a rock in Natural Bridge State Park.