This half-finished "city of toys" was almost Italy's own Las Vegas.

Known for centuries as the famous Roman emperor's burial place, this monument is actually something else.

Rome's ancient Etruscan rival, now a park full of ruins.

Art and armour fill every inch of this rich kid's Italian villa.

A lover's walk between hilltop towns, decorated with graffiti love notes.

Italian cave with exceptional acoustics and an unsavory history.

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

The sinister ruins of one of the worst dam failures of the 20th century lie in this astonishing alpine setting.

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

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

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

Virgil's many-mouthed gateway to the underworld.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

An ancient artistic garden parlor full of hidden water wonders.

This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

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

Venice's island of the dead.

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

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

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

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

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.

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