A former plague hospital turned medical museum.

This disused Cold War bunker has been restored to all of its early 60s glory.

Follow the original medieval paths that wind through this intriguing section of the city.

A wunderkammer of curious objects and intriguing art nestled within a hub of ancient Roman sites.

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

Its interior is adorned with some of the best examples of early Christian mosaics.

Roman-era ships unearthed...

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

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

This large, circular tomb is the final resting place of the first emperor of Rome.

One of the most important yet well-hidden museums dedicated to the history of medicine.

The Pope’s secret escape route.

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

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

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

2300-year-old Roman road connecting the empire.

The underground sanctuary of a mysterious ancient cult.

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

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."

This museum is filled with an eclectic collection of unique inventions.

The elegant manor house where Kaiser Wilhelm II lived in exile after World War I.

In the Netherlands, one of the world's largest private car collections can be found.

This massive collection of taxidermy is full of specimens collected by missionaries during their international travels.