The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

An off-the-beaten-path place to literally hang beneath Milwaukee's Holton Street Bridge.

This was once the largest four-sided clock in the world (yes, even bigger than Big Ben).

Built in France in the 1400s, this gothic chapel now resides at Marquette University in Milwaukee, Wisconsin.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

Fortified medieval tower house with lovely roof garden.

Ancient snack bar of the Roman Empire re-opened.

The walls and streets of the ancient city are peppered with penises.

Before it was buried by volcanic ash, this fast-food restaurant fed the hungry hordes of ancient Rome.

Erotic art covers the walls of the largest ancient pleasure palace.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

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

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

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

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

2300-year-old Roman road connecting the empire.

Rome’s legendary peephole vista is also a former Crusader stronghold.

Scattered throughout London are ancient remnants of the city's former bounding wall.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

One part local history, 99 parts gruesome haunted house.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Legend says this sacred tree was a gift from goddess Athena.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.