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

An 18th century fountain and two columns are all that remains of Rome's forgotten river harbor.

A hospital where antique dolls are given new life.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

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

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

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

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

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

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

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

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.

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

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

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

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

This statue is the only female representation of Rome's "talking statues."

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

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

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

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

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