Hidden within a Netherlands crater is a stone bed that lets those who lie in it see the sky as a curved surface.

One of the oldest and largest wooden churches in France was very evidently constructed by shipbuilders.

This lesser-known Frank Gehry building houses a treasure trove of cinema history.

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

Once designed as the entrance to Buckingham Palace, this structure was later relocated and stands as a victory arch.

The Great Fire of London and the regulation of one-way streets both started in this alley.

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

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

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

The commemorative stone column conceals a secret laboratory.

The ritual has been performed uninterrupted for nearly 700 years.

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

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

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

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

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

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

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

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

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

This coffee shop lies hidden beneath a historic church.

After nearly 60 years, there's still a bear at Paddington Station looking for help.

Hear the quietest sound from across the dome.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.