The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

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

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

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

Perched above the bustling town of Kerak is a sprawling, ruinous castle that has witnessed nearly a millennia of Levantine history.

Gladiators battle and chariots race daily in the ruins of a once-great Roman city.

This ancient town is full of stunning Ottoman architecture and streets so narrow trash collection is done by donkey.

The world's oldest map of the holy land gives us a fragmented glimpse of the layout of biblical nations.

An ancient fortified mound raised over the millennia from settlements built one on top of the other.

This headstone marks the grave of an 11-year-old boy killed during clashes in the streets over the boycotting of British goods.

Historic Hull Street was actually the first street with a proper name in the Boston area.

Stolen goods adorn the organ at Old North Church.

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

A pair of gigantic baby heads greet passengers at Atocha Station.

An ancient Egyptian temple in the middle of Madrid, Spain.

A rare set of strings by famed instrument maker Antonio Stradivarius is on display in the Royal Palace.

An iconic and controversial ancient Iberian funerary urn with a hauntingly penetrating gaze.

This small museum tucked within a subway station holds pieces from Madrid's past.

A whimsical brother of the nearby Fallen Angel statue takes the falling part quite literally.

An enormous, inside-out glass globe built in 1935.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

Climb atop one of the world's longest and heaviest trains for an unbelievable journey across the Sahara Desert.

Founded in 670, this ancient mosque is an architectural time portal.

The ancient heart of Tunis is an enormous maze of narrow streets and alleyways.