The abandoned zoo enclosures offer a perfect place to experience the other side of the bars.

The remains of the second-oldest zoo in Europe can be seen within these library gardens.

A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

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

Legend says this mysterious stone head belongs to a woman who was petrified by an alchemist.

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

An incredible menagerie of more than 3 million taxidermied animals at the oldest science museum in Europe.

The middle finger of modernity.

Hidden within this iconic mountain are a set of World War II bunkers once used by German forces.

This subterranean shrine beneath a bike rental store celebrates the iconic Italian scooter.

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

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

A forgotten "city of water" underneath the famous Trevi district.

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

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

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

One of seven Jewish catacombs in Rome and one of only two open to the public.

A hospital where antique dolls are given new life.

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

A collection of objects supposedly singed by the hands of souls in purgatory.

The Pope’s secret escape route.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.