This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

360° views of the city plus five floors of optical illusions and hands-on science.

Ruined 11th century abbey built by King David I in Edinburgh, Scotland.

Believed to be the remains of the lost Temple of Minerva, this nymphaeum has been known by its misnomer to this day.

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

An ancient Roman temple first dedicated to an emperor's wife is now a church.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

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

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

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

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

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

Roman-era ships unearthed...

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

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

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

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

A Nesting Doll of Churches.

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

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

Jesus' footprints and the first catacombs in the world.

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

2300-year-old Roman road connecting the empire.