Virgil's many-mouthed gateway to the underworld.

Walk through a fairytale in Tuscany.

Ancient snack bar of the Roman Empire re-opened.

An ancient artistic garden parlor full of hidden water wonders.

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

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

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

This picturesque Umbrian city has a subterranean side that has long remained hidden.

Dramatic sea stacks adorn the coast of this small village on the Adriatic coast.

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

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

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

The astonishing collection of an infamous criminologist.

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

An incredible menagerie of more than 3 million taxidermied animals at the oldest science museum in Europe.

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

Medieval town turned hippie commune, once home to the secret foreskin of Jesus Christ.

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

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

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

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

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

Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

This abandoned Brutalist treehouse is a hidden architectural relic.