One of the oldest medical collections in Europe focusing on rare surgical instruments.

Abandoned railway line circling the city of Paris.

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

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The oldest stone house in Paris was built by its most famous alchemist.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

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

Crawling into this primordial cave may feel disconcertingly familiar.

Finnish lake, and scene of an infamous murder mystery.

Quality time with reindeer in the stunning scenery of their natural Lappish habitat above the Arctic Circle.

A collection of collections ranging from dentistry to minerals.

This lake-bound geographical marker sits at the point where three European countries intersect.

Legend has this precariously placed rock was placed by giants. Science has another explanation.

An alien church provides much needed silence in the midst of a Finland shopping center.

Architecturally stunning library serves as the hub of Finnish scholarly life and culture.

This fantastical icy castle is built anew every winter.

Rent out a glass igloo to watch the Northern Lights like you live in the future.

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

Two massive boulders, rocking back and forth with the ebbing of the sea.

This isolated structure beckons adventurers with sublime views of the Faroe Islands.

This remote island village was in danger of depopulating completely until a tunnel was built to connect it to the rest of the world .

Estonia's largest creative city is a vibrant bohemian hub located within a former industrial complex.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

Nearly 40 miles and 1,000 years of limestone mines under Denmark.