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

A Parisian exterminator's shop whose storefront displays stuffed rats hanging from traps.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

With a history of slaughter, feast, and famine, remnants of the pork industry decorate this area--even its church.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

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

Executions were once held near this beautiful 18th-century fountain.

This small, ingenious cannon once helped regulate Parisian life.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

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

The bar where "The Great Train Robbery" was planned was once a nexus of high society and low morals.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

This London marker celebrates the spot where the world-famous English band was founded.

The collection contains over 25,000 items and details the painful dental practices of the past.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

Eighty million natural history specimens call this gargantuan museum home.

A little slice of Japan and its aesthetics in London's Holland Park.