Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

A sculpture serving as an homage to Pope John Paul II.

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

An alchemist's “magic door” stands in the middle of a Roman park.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

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

Nobles would stage mock naval battles on this large lake at the Royal Palace of Caserta.

This tiny islet has somehow housed an ancient temple, two monasteries, a church, a fortress, and a restaurant.

The only visible remains of this ancient Greek underground temple is its roof protruding from the earth.

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

Ride a boat through this magnificent underground world, which now doubles as a theater.

The tallest statue in Italy is also one of the world's tallest statues of Jesus.

The abandoned ruins of a failed resort hide on this verdant, picture-perfect island.

Constructed during the 1960s, this bridge is still the highest in Italy.

A fairytale-like medieval church perched atop a rocky cliff on Italy's "Coast of the Gods."

The ruins of this medieval castle now stand as a monument against all wars.

This small but lovely sinkhole lake is the last remnant of a great prehistoric water basin.

The pristine waters crossing this forest form a hidden waterfall among the dense vegetation.

An Italian hillside ghost town.

People have been living in the cave houses on this Italian hillside since the Neolithic era.

Skulls and skeletons are omnipresent in this church dedicated to souls trapped in purgatory.

An abandoned quarry hides an open-air gallery of huge sculptures, some made from the rubble of 9/11.

Its look is severe, but its location, isolated on a hill in the middle of the countryside, is particularly scenic.

The construction of a new church near Venosa was started in the 11th century, but never finished.