A sculpture serving as an homage to Pope John Paul II.

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

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

The final resting place of the poets Shelley and Keats.

Romans decided this 16th-century "talking statue" was so ugly, they named it after a primate.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

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

Rome's semi-secret peephole vista is also a former Crusader stronghold.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

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

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

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

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

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

A statue representing a lost Roman profession that was vandalized for centuries.

A massive marble foot is tucked away in a small alley near the Pantheon.

Plaques on its facade commemorate the Tiber's most destructive deluges.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

A deep mark on the remains of a Roman temple, believed to be left by a legendary warrior.

An 18th-century post box used to alert the church of sick and ailing foreign pilgrims.

A stunning gilt bronze relief denounced by Hitler as "degenerate art"—even though it was dedicated to the Nazi leader.

A line of disused military bunkers built to defend against Nazi invasion lies hidden on the outskirts of the city.

This spaceship sculpture in the middle of the Slovakian capital looks like it just crash-landed.

A massive sculpture of an obscure Celtic coin that has become a symbol in Slovakia.