These barriers stand as stark reminders of Northern Ireland's troubled past.

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

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

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

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

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

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

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

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

The first declared National Monument in the United States.

The world's largest mountain carving could fit all of Mount Rushmore inside it many times over.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

Former utopian colony based on the belief that the universe exists in a hollow sphere.

A fitting attraction for the corn capital of the world.

The palatial McDonald's that inspired Wesley Willis.

In one Chicago park, a trio of werewolves are waiting to devour their fallen brethren.

An outdoor urban gallery of large-scale artworks by the world's most influential street artists.

Theater has had many different incarnations but has survived the ravages of time.

In a quiet north Chicago neighborhood rests a stunning relic of the golden age of earthenware design.

Once called the "Polish Gold Coast" it is an icon of the neighborhood that bears its same name.

Fragments of architectural wonders from around the globe are embedded in the newspaper building's walls.