This grand hydraulic installation has provided water for townspeople since the Middle Ages.

Some believe this abandoned Brutalist masterpiece inspired George Lucas's Sandcrawler.

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

The largest salt lake in the Sahara is mysteriously alluring.

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

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Cold war icon and onetime "hole" in the iron curtain.

A restaurant and observation deck built in a unique broadcasting antenna.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

This snug medieval lane is one of the narrowest streets in the world.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This elaborately decorated, fairytale-like Romanian royal palace is one of the most striking castles in Europe.

A striking symbol of the Bulgarian capital.

This historic black and white monastery is one of Bulgaria's architectural jewels.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

Ancient serpentine sacrifice holder that has stood the test of time.