This modest marker near Notre Dame identifies the very center of Paris.

The oldest stone house in Paris was built by its most famous alchemist.

France's most famous cemetery, with some of its most curious tombs.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A small window on Via Piella offers a lovely and rare peek at Bologna's lost canals.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

A dead saint, a deadly poison, and a mysterious holy ooze.

The "Great Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

The oldest volcanology research center in the world.

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

The Emperor Tiberius' palace of debauchery.

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

The incorrupt tongue of the patron saint of lost things is venerated in this basilica.

Built to repay the sins of the father, this church is home to one of the most valuable works of Western art.

Southern Italy's spinning top village.

A fake medieval village in the middle of Turin.

Italian poet Dante Alighieri is entombed in this small mausoleum in Ravenna, and his hometown of Florence has never been too happy about it.

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

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

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

Ancient snack bar of the Roman Empire re-opened.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.