The old observatory in Copenhagen has a spiral corridor used as a racetrack.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Hans Christian Andersen for the postmodern world.

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

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

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

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

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

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

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

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

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

Breathtaking and huge 430 year old maps of Italy.

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

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

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

A small 12th-century temple surrounded by waters believed to have curative properties.

The statue honors a beloved bird that once roamed St. George's Market.

This massive monument has been telling the time for 150 years—at a slight angle.

For part of the year, this innovative greenhouse is painted white to keep the plants from getting scorched.

This sculpture commemorates Edinburgh's sister city and their respective celebrity dogs.