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.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

A Black Forest cuckoo clock theme park features one timepiece big enough to walk inside.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

A striking 12th-century-style castle built on the edge of a cliff.

The fairy tale castle of the "fairy-tale king."

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

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

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

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

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

This water tower slanted at an uncomfortable angle off the old Route 66 was an ingenious marketing ploy.

Once in disrepair, this popular Texas stop along iconic Route 66 has been restored to its past glory.

A pair of giant legs paying homage to a poem, a king, and it would seem, socks.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

The time thousands of bags of chips washed ashore in the Outer Banks is memorialized in a local museum.

The high point on the 16th president's eponymous roadway is marked by a massive version of his head.