A labyrinth hides in plain sight at each of the city's 270 Tube stations.

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

Near the site where the English Archbishop was born, you can find an emblem in the shape of a pilgrim's badge.

The library houses an incredible collection of some of the world's most impressive books and manuscripts.

Never actually a tree at all, this spot was the site of London's public hangings for nearly 600 years.

This plaque in one of London's oldest public hospitals commemorates the first meeting of two of Britain's most famous literary heroes: Sherlock Holmes and Dr. Watson.

An eccentric Victorian aristocrat's enormous collection of medieval armor and weapons from around the world.

The bridge is a secret gallery of discarded gum that has been transformed into miniature masterpieces.

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

This macabre painting of a Shakespearean scene looks like something out of a nightmare.

This mysterious and unique painting is filled with symbolism.

A haunting painting meant to capture the calamity of World War I.

This haunting sculpture was created as a statement on the mechanized warfare of the First World War.

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

This open-air mosaic gallery honoring an English artist took hundreds of volunteers more than seven years to create.

This bewitching Babylonian goddess haunts a hallway of the British Museum.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

A cluttered and astounding collection of antiquities and curiosities.

More than a million titles fill the labyrinthine shelves of this prestigious private library.

Giant, friendly pelicans in Central London, the most unlikely of places.

The bronze uniforms commemorate the vital role of women during World War II.

The sumptuous ceiling was one of the last things Charles I saw before his execution.

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

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.