Follow the original medieval paths that wind through this intriguing section of the city.

Its collection includes a broad array of social, geographic, graphic design, and political history.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

This coffee shop lies hidden beneath a historic church.

Hidden beneath the streets of London is a secret subway that only carried mail.

A large portion of this navigable canal runs under Paris's famed boulevards.

The Sun King's military models, saved from the Louvre.

This banal Parisian entranceway is not what it seems.

The curious underground history of keeping Paris clean.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

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

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

France's national museum of scientific and industrial instruments.

A haunting collection of the vanished and disappearing natural world.

Abandoned railway line circling the city of Paris.

Natural history museum celebrating biodiversity with a parade of taxidermy animals.

This museum houses an imposing skeleton army comprised of creatures great and small.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

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

There has been an astronomical clock on this spot since the 14th century.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

Visitors dating back to the 1600s carved their marks in the stones of the iconic tower.

This unusual piece of Renaissance art depicting the bodily horror of crucifixion and skin disease may have been inspired by fungus-induced hallucinations.