The roof of this ancient mausoleum is made from a single Istrian stone weighing a massive 230 tons.

These artificial caves crafted by ancient Romans were elaborate fish farms for moray eels.

When a massive landslide hit one of the world's tallest dams it created a tragic environmental disaster.

The only substantial part of Nazi Germany's formidable defensive line through Northern Italy that survives today, largely intact.

This old medieval prison tower has been a site of astronomical research for more than 250 years.

A medieval wash house where people washed clothes in a river allegedly formed by the tears of a mourning nymph.

Was this cave created by Hercules's wrath, the devil, or volcanic activity?

This lesser-known leaning tower is all that remains of the medieval castle of Vernazzano.

An unusual resting place built into the hill with an amazing view of Lake Como.

A long-buried ancient ruin unearthed right in the middle of the city.

Believed to be the remains of the lost Temple of Minerva, this nymphaeum has been known by its misnomer to this day.

This deconsecrated church has seen many uses, from a tobacco storehouse to a cinema.

Built to be the ideal penitentiary, this abandoned panopticon saw several revolts and even a prisoners' coup.

According to the legend, this structure was built in a single night with the help of the devil.

This Roman underground canal was the longest tunnel ever built until the late 19th-century.

Legend said this huge, gnarled tree sheltered the saint during a storm.

A series of caves, tunnels, and wells filled with fascinating figures and symbols.

A massive bridge forms part of an aqueduct that was deemed an architectural wonder of its time.

One of Rome's most picturesque and original bridges was also a popular choice for Grand Tour artists.

Also known as the Temple of Poseidon, this is one of the best-preserved Greek temples in the world.

A colossal aqueduct from the second century B.C., deeply hidden in a gorge on the outskirts of Rome.

A 17th-century doorway in a small Sabine village is a portal into the mysteries of alchemy.

For decades, vendors have sold clothes once worn by American soldiers who stormed Italy in the 1940s.

A statue representing a lost Roman profession that was vandalized for centuries.