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

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

Five candy-colored villages on the Italian Riviera.

A fairy tale castle in modern Rome.

The underground sanctuary of a mysterious ancient cult.

The glowing blue Nymphaeum of Emperor Tiberius.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

A unique Tuscan hideaway acts as an art mecca as well as a hotel.

Eco-village hidden in the foothills of the Alps that created a massive system of psychedelic underground temples.

This giant middle finger statue sends an unambiguous message to Italy's bankers.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

Virgil's many-mouthed gateway to the underworld.

Geothermal waterfalls in Tuscany.

This 16th-century monastery has been turned into a surrealist architecture compound.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Architectureal fantasy quarter of Rome.

Renaissance villa and gardens complete with a tormented colossus.

A 16th-century horror show built in a lovely Italian garden.

When ecosystems collide in the arid Southwest.

This angular Dwarven tunnel cuts through a mountainside in Glacier National Park.

With over 340,000 artifacts and counting, there is something for everyone, often called the "Smithsonian of the West."

See the computer’s history revealed over the course of 20,000 years.

This charmingly homemade amusement park has been growing for 40 years.

On the Oregon coast there is a natural hole that seems to be draining the sea.