This caldera was once associated with the Etruscan god of the underworld.

This medieval Italian village was transformed into an architectural marvel by the famous "Papessa" Donna Olimpia.

Water and windows define this defensive Italian well.

A Roman calendar dating to the first century is tucked away in a small town alley.

Does this strange mural depict witches battling beneath a penis tree?

This Roman theater was crafted into the local tuff rock and was rediscovered during the 19th-century.

The remains of a town so thoroughly destroyed by French forces that the citizens simply left.

The ruins of this once gorgeous medieval church are still standing, despite the region's constant flooding.

This medieval oratory decorated in magnificent frescos was constructed after Charlemagne received a vision.

A fairy-tale-like forest that was sacred to Jupiter and Saint Anthony.

Naturally protected city carved from a rock face.

Mausoleum and Holy Seat of Antiochus I of Commagene.

A sacred lake with thousands of sacred carp and a biblical history.

A former ironworks that was the first UNESCO industrial site.

A tiny chapel clings to a precipice above Germany’s gemstone capital.

A university observatory dome painted to resemble the beloved 'Star Wars' droid.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

The last bastion of Roman presence north of the Alps looms over a German town.

The prototype for all Nazi concentration camps.

This mine is home to the largest man-made hole in Europe.

A beautifully eclectic mix of architectural styles.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

Debatably clever, or just plain honest hotel advertised as "The Worst Hotel in the World."