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

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

All that's left of the quintessential "cabin in the woods."

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

This park on the outskirts of Rome boasts two ancient Roman aqueducts and a medieval tower.

Charles Dickens was not a fan of the ghastly wall dressings in this 6th century church.

A burial vault located under Tiber Island in the middle of the Italian capital.

This ancient trail climbs the mountain where a Latin League cult worshipped Jupiter, its main deity.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

This gallery commissioned by Cardinal Spada is known for its magnificent optical illusion.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

This is the oldest Roman-made bridge in the city still existing in its original state.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

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

Ancient ruins hidden underneath a modern luxury hotel.

This curious, round temple is the oldest still-standing marble building in Rome.

The studio built by fascists in the hopes of "reviving the film industry" with the occasional propaganda film opportunity thrown in.

This ancient market is often referred to as the oldest shopping mall in the world.

A modern sliver of architecture in Roma.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

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

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

An Italian ghost town that fought obscurity, until a mysterious illness brought it to its knees.

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