Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

It houses the remains of a 17th-century version of the Titanic.

The great polar explorer is remembered in this far northern town, where he embarked on his final expedition.

This functioning parish church is also the site of many concert performances due to its wonderful acoustics.

The design of this beautifully crafted building was inspired by Norwegian glaciers.

At the very tippity-top of Europe is a cliff from which you can view the midnight sun.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

Hamburg's first legal sex work is relegated to a gated street that still does not allow pedestrian women.

Something's missing between the arcades of the Palazzo della Ragione in "the city of the three withouts."

The tomb of the mythological founder of Padua is not hidden in some obscure crypt, but stands right in the middle of the city square.

The incorrupt tongue of the patron saint of lost things is venerated in this basilica.

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

A whimsical bridge adorned with decorative dragons.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

A miniature train-ride through Slovenia's largest cave system.

The "dragon babies" of southeastern Europe.

This one-time health resort was used by aristocrats around the world.

The largest ice cave in the world is thought to be the entrance to hell according to Austrian legend.

The prison where Hitler wrote "Mein Kampf," and 278 Nazis were later executed for war crimes.

César Baldaccini's iconic sculpture of a 40-foot thumb stands tall in La Défense.

The mummified heart of Louis XVII, the lost dauphin of the French Revolution.

Inside a former cabaret, seven floors of erotic art.

The celebrated eyesore created by starry-eyed sweethearts.

The smallest port in France is named after the pirate who created it.