Stockholm's deepest subway station is also a stunning ecological wonder.

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

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

Finland's northernmost zoo is home to the country's only polar bears.

A cathedral resurrected from the ashes of one of Europe's greatest urban fires.

Finland's oldest astronomical observatory once played a crucial role in seafaring and timekeeping.

If you visit Santa's village, you can get your passport stamped to show you crossed into the Arctic Circle.

Roughly 17 million letters to Santa have found their way to this Arctic Circle post office.

A replica of the home of a famous fictional troll family.

This endearingly discomfited urinating statue commemorates the sneaky pees had by us all.

A subterranean house of worship carved right out of the bedrock.

A preposterously luxurious hotel with gold-plated iPads, Rolls Royce chauffeurs, and a staff that trains by watching "Downton Abbey."

This artificial archipelago was supposed to resemble a map of the world.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

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

The first modern cemetery of Lyon is complete with more than 200 chapels and monuments.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Notorious artist squat renovated into legal studios.

An imperial fortress city that incorporated cultural elements from the entire Mughal empire, only to be abandoned the year it was finished.

An elaborate Mayan city shrouded in alien conspiracy revealed the tomb of Pacal the Great.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.