A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

An incarceration museum on the spot of possibly the oldest prison in England.

Hear the quietest sound from across the dome.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

One part local history, 99 parts gruesome haunted house.

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.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

A fairy tale castle in modern Rome.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

This ancient market is often referred to as the oldest shopping mall in the world.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

2300-year-old Roman road connecting the empire.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Drink wine handed out through a window as part of an age-old tradition.

An extra-wide chair built to accommodate the former president's big behind.

Yale University's home for rare works, including the mysterious Voynich Manuscript.