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

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Venice's "Island of the Mad."

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

The marble facade hides a little-known medical museum with early surgical instruments and rare copies of canonical texts.

Originally a leper colony, the island is now an Armenian monastery that's home to an incredible manuscript library and eclectic museum.

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

The walls and streets of the ancient city are peppered with penises.

Buried next to Pompeii, this lesser-known Roman villa was the opulent vacation home of Emperor Nero's wife.

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

The mystic whose incorrupt corpse still attracts the faithful.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

One of the most important yet well-hidden museums dedicated to the history of medicine.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

A hospital where antique dolls are given new life.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.