Venice's island of the dead.

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

100 year tradition of fist fights, marked by marble footsteps.

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

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

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.

A Nesting Doll of Churches.

The final resting place of the poets Shelley and Keats.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

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

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

Architectureal fantasy quarter of Rome.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

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

A whimsical bridge adorned with decorative dragons.

A miniature train-ride through Slovenia's largest cave system.

This one-time health resort was used by aristocrats around the world.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

Gargoyle head that brings good luck.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

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

Macabre symbols of death and mummies on display set the tone of this Italian purgatory church.