Scattered throughout London are ancient remnants of the city's former bounding wall.

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

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

A local student's chance encounter with Keith Haring led to the creation of one of Europe's largest murals.

Elaborate tile work in this railway station tells the story of Portugal.

A hidden three-foot-wide house separates these two regal churches.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

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

In the past, Renaissance sex workers were encouraged to entice customers on this bridge.

Where Venice's gondolas go for a tune-up.

Two stone columns flank the grand Venice square, but there were supposed to be three.

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

Every day is like Christmas on this street where the traditional Neapolitan nativity scene comes to life.

This medieval city gate is now a blend of the past and the modern world.

Pompeii's less famous neighbor is still revealing her secrets.

Before it was buried by volcanic ash, this fast-food restaurant fed the hungry hordes of ancient Rome.

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

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

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Ancient snack bar of the Roman Empire re-opened.

Memorials at a Florence railway station remember the citizens who were deported from Italy and sent to extermination camps.

Secret refuge and museum of the Duke of Florence.