This Italian foot path winds through the mountains via 52 individual tunnels.

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

One of the largest caves in the world open to the public.

The mystic whose incorrupt corpse still attracts the faithful.

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

Where Aleister Crowley taught magick in "La Chambre Des Cauchemars," his "Chamber of Nightmares."

This mosaic-lined medieval church was built by the world's first admiral and still holds mass in ancient Greek.

A complex, nine-layer maze on the grounds of a Venetian doge's playground.

This curious, round temple is the oldest still-standing marble building in Rome.

Crossing this suspension bridge feels like walking through the sky, a fitting tribute to the head of the Apollo program.

This abandoned Brutalist treehouse is a hidden architectural relic.

The astonishing collection of an infamous criminologist.

This real life asylum of horrors is now an abandoned ruin that hides the unbreakable code to one patient's insanity.

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

Hanging within this medieval church are the bones of a beast allegedly slain by a fourth-century saint.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

Armenian monks at an island monastery in the Venetian Lagoon make a rare rose petal jam.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

The Sighignola summit on the Swiss border offers views so breathtaking it's been named one of the most beautiful places in Italy.

An Italian ghost town that fought obscurity, until a mysterious illness brought it to its knees.

This Tuscan lake hides a 13th century town that is still visible when the water recedes.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.