The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

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

Gods clash with machines in a power plant regenerated as a museum.

The meaning behind this triumphal Roman arch was a mystery until the early 20th century.

A colossal aqueduct from the second century B.C., deeply hidden in a gorge on the outskirts of Rome.

Known for centuries as the famous Roman emperor's burial place, this monument is actually something else.

Hidden within this iconic mountain are a set of World War II bunkers once used by German forces.

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.

An abandoned Roman salami factory has found new life as an art space home to 200 squatters.

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

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

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

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

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

The final resting place of the great navigator, or maybe his brother.