The house where a Danish physicist discovered the connection between electricity and magnetism.

France's national museum of scientific and industrial instruments.

Walk upon the mementos of the dead in this Parisian courtyard paved with medieval tombstones.

Lyon's "Wall of the Silk Weavers" is one of the largest murals in Europe.

This ancient Roman arch misled treasure hunters for centuries.

In Rome’s Jewish ghetto, a 200-year-old bakery still makes the neighborhood’s historic sweets.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

2300-year-old Roman road connecting the empire.

An alchemist's "magic door" stands in the middle of a Roman park.

Architectural monsters are devouring this palace's every door and window.

Secret refuge and museum of the Duke of Florence.

Originally a leper colony, the island is now an Armenian monastery that's home to an incredible manuscript library and eclectic museum.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

This artificial cave looks like something out of a fairytale.

A sweet museum focused on beets.

A portable, wooden replica (minus the hyphen) of Hamburg’s iconic crooked coffee shop.

Come stay at a live-in art installation.

A 12th-century fortress containing some of Berlin's oldest buildings.

This museum is dedicated to the little known ancient Roman history of Vienna.

The housing complex served as an anti-fascist fortress during the Austrian Civil War.

A spherical "micro-nation" in the heart of Vienna.

One man's personal collection of KGB memorabilia is presented along with his strange viewpoint.