Legend has it that this bronze orb, which sat atop an ancient Egyptian obelisk, once held the ashes of Julius Caesar.

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

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

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

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

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

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

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

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

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

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

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

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.

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

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

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

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

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

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

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

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

The Pope’s secret escape route.