This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

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

This demon atop the Notre-Dame de Paris looks utterly bored.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Hear the quietest sound from across the dome.

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

There's an exclusive Beefeaters pub hidden in 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.

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

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

This one has sailed five times as far as Sir Francis Drake's famous ship.

An incarceration museum on the spot of possibly the oldest prison in England.

The television series' iconic giant foot was borrowed from this classical painting.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

A clock designed to run with perfect accuracy for 10,000 years.

Charles Babbage's proto-computer, painstakingly brought to life.

This innovative steam machine was no doubt the most famous of the pioneer locomotives.

Eighty million natural history specimens call this gargantuan museum home.

The "beautiful" equation predicting the movement of all electromagnetic particles is engraved in front of Newton's tomb.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.