The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

A forgotten "city of water" underneath the famous Trevi district.

This winding road through an Italian canyon may be the most scenic drive in the world.

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

Virgil's many-mouthed gateway to the underworld.

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

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

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

This large, circular tomb is the final resting place of the first emperor of Rome.

The remains of a town so thoroughly destroyed by French forces that the citizens simply left.

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.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

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

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

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

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

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

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

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

Drink wine handed out through a window as part of an age-old tradition.

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

Dug as a secret royal escape route, the tunnel became a wartime bomb shelter and dumping ground for vintage cars.

The location of the last witch trials of Italy, known as "The Salem of Europe."