This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

A little known pile of scraps and plaques mark the grave of a downed RAF bomber.

A plaque commemorates the spot in the Oregon woods where the first-ever Geocache was hidden.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

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

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

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

Ship-sized kinetic sculptural fantasy.

Eighty million natural history specimens call this gargantuan museum home.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

Catacombs turned marketplace.

Hear the quietest sound from across the dome.

An unusual round church in London with a Templar past.

Macabre astrological automaton clock dating to the late 1400s.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

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

Take a steam-powered ride straight out of the past on this Appalachian rail line.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

The highest point in Washington state is a volcano covered in glaciers.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

For the holidays, the tallest broadcasting tower in the Netherlands turns into one of the world's tallest Christmas trees.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

The most famous location in China was home to whole dynasties worth of imperial rulers.