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

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

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

The yawning maw of this pagan visage is said to bite off the hands of liars.

Jesus' footprints and the first catacombs in the world.

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

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

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

This strange bovine gargoyle is said to have been put in as a passive aggressive form of revenge.

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

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

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

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

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

A lover's walk between hilltop towns, decorated with graffiti love notes.

Five candy-colored villages on the Italian Riviera.

Unconventional site where the tracks of Zurich tramcars intersect.

This is not only one of the oldest collections in Europe, but also possibly the most beautiful.

This magnificent Crimean estate was once a playground of the Russian elite.

A castle perched precariously over the Crimean Sea.

"Holy Wisdom" overlooks the city that became its namesake.

Sofia's legislative center is continuously reinventing itself.

A vast Communist-era exhibition space in the Bulgarian capital.

A striking symbol of the Bulgarian capital.