Bad farming practices caused this unnatural natural wonder.

The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

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

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

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

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Ancient snack bar of the Roman Empire re-opened.

Erotic art covers the walls of the largest ancient pleasure palace.

Small on the outside, big on the inside, this church is an astonishing act of visual deception.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

Da Vinci's equestrian statue, 500 years in the making.

In Florence's great Duomo, a 26 foot fresco honors a mercenary famous for attacking Florence.

Secret refuge and museum of the Duke of Florence.

A slightly creepy gallery of plaster cast models in the same museum as Michelangelo's David.

It’s said this crypt was the setting for the tragic finale of the Shakespeare play.

A whale rib was used to advertise the store by the arch that offered exotic goods from far away.

Pilgrimage site for star-crossed lovers.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

Two stone columns flank the grand Venice square, but there were supposed to be three.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

Go inside to really appreciate this 500-year-old technological masterpiece.

As can be expected from a centuries-old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.