A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

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

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

The relics of dozens of martyrs are stored in a single chapel.

Cave shrine on Monte Pellegrino.

Time has been frozen at this station since the bombing in 1980—or so it was believed.

In the world's oldest university is a stunning 17th century anatomical theater carved from spruce.

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

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

The graveyard is filled with beautiful funerary art and boasts breathtaking views of Florence.

Secret refuge and museum of the Duke of Florence.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

The oldest operating pharmacy in the world features 800-year-old recipes.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

At Monet's beloved home you can still see the Japanese bridge, waterlilies, and weeping willows that were the subjects of some of his most iconic paintings.

Located in the house where Gustave Flaubert was born, this odd museum has more to do with medical grotesquery than the Western novel.

An ancient ossuary in Rouen.

The mountaintop inspiration for Umberto Eco's "The Name of the Rose."

An incredible mosaic-lined monument said to have held the remains of an ancient Roman empress.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

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

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.