This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

The "Seinfeld" diner.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

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

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

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.

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

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

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

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.

The oldest apple tree in the Pacific Northwest.

This quirky piece of naval artillery has been deafening Canadians for over a century.

What happens when a sculptor has to find a way around a 100-year-old copyright.

The first public library in the Americas has more than 45,000 books dating back to the 15th century.

This colossal ancient jaguar sculpture was used as a vessel for the hearts torn from sacrificial victims.

The unique collection often goes unnoticed by visitors focused only on the archaeological objects.

The striking jade death mask of an ancient Maya king is displayed in a replica tomb in Mexico City.

Gilded heaven for philatelists and architecture freaks, still in full working order despite sitting atop tremulous ground.

An Aztec temple, the largest man-made pyramid in the world, sits buried in earth with a Spanish church set on top.

Since the 1700s, this old barrel has acted as a post box that relies on the kindness of travelers.