Notorious artist squat renovated into legal studios.

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 history of radiation is on safe display at the foot of a radiation science laboratory.

The curious underground history of keeping Paris clean.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

A massive explosion that leveled hundreds of buildings in the city of Leiden is remembered by a waterside plaque.

Science meets wall art to highlight the beauty of famous mathematical equations.

Devious political maneuvering and four ancient, working telescopes are central to the world's second-oldest observatory.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

The works of poetry's biggest names grace the walls of the city of Leiden, all carefully painted by hand.

One of the great math minds of the 17th century is underfoot in this 900 year old Dutch church.