The homestead of American patriot John Adams.

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.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

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

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

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

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

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

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

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

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

A makeshift shrine to the late rock star is still kept up on the nondescript façade outside 1 Logan Place.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

Richard III supposedly disposed of his nephews' bodies here in an effort to seal his claim to the throne.

Graffiti from the 16th and 17th centuries cover the walls of this part of the Tower of London.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Scattered throughout London are ancient remnants of the city's former bounding wall.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

Hear the quietest sound from across the dome.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.