On a wall in linear London, a plaque hangs at the high water mark of one of the worst floods in fictional Kcymaerxthaereal times.

Charles Babbage's proto-computer, painstakingly brought to life.

A clock designed to run with perfect accuracy for 10,000 years.

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

Art and a pun, all in one.

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

A musical instrument played by the sea.

Museum dedicated to the terror regimes of Hungary.

Once the home of a hermetic monk, this cave now houses a small church.

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

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

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

This folk museum is devoted to small figurines of provincial village life.

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

The prototype for all Nazi concentration camps.

France's most famous cemetery, with some of its most curious tombs.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

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

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

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

One of the longest wooden benches in the world snakes around Geneva's Treille Promenade.

Large Hadron Collider and the Birthplace of World Wide Web.

Men in rubber-soled boots serve as your "brakes" on this toboggan ride Hemingway described as "exhilarating."

This abandoned Slovenian military barracks has become a punky-political art squat.