Ruins of a German castle on top of a towering stone pillar.

The city of Parma's cathedral is home to one of the greatest illusionistic frescoes of the Renaissance.

A striking memorial recalls thousands of Bolognese men and women killed fighting fascists in World War II.

Over 100 towers were built in Bologna during the Middle Ages, but only 22 survive.

The intricate geometry inside this Baroque-style dome was designed to create "terror of the human soul."

An ancient Greek monument and a Byzantine church coexist inside this cave.

View the ancient remains of buildings and the ancient "River of Hades" before hopping on a train.

Where commuters walk through remnants of an ancient Greek necropolis.

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.

An ancient octagonal weather station named for the eight Greek gods of wind.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

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

This ancient statue of Dionysus lies unfinished and abandoned in one of Greece's oldest quarries.

Go deep down into the earth to experience the world of Welsh coal miners.

Recently restored menagerie of Victorian-era beasts.

The Stonehenge of Wales is one of the grandest neolithic dolmens still in existence.

At first glance, little checkered structures on the hillside look like they house the living, not the dead.

Iceland's tribute to its thankless civil servants.

This stunning concert hall has become a symbol of Iceland's national recovery.

This natural Icelandic fissure allows divers to swim right between two volatile tectonic plates.

The oldest (maybe) swimming pool in Iceland is a stunning oasis built into the side of a lush hill.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.