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

Paris' linguistic guide to the international language of, yes, love.

On La Gomera, "Silbadors" communicate in a 4,000-word language of whistles.

There might not be much left of these Irish ruins, but their linguistic legacy is still going strong.

14th century Norse artifacts in Northwestern Minnesota could have proved a Viking landing before Columbus.

This massive library holds what was once the largest book collection in the world.

Abandoned railway line circling the city of Paris.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

Where the high court feasted, frolicked, and high courtesans put their royal lovers' diamonds to the test.

19th century pendulum and a clock restored by a rogue group of guerilla artists.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

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

After nearly 60 years, there's still a bear at Paddington Station looking for help.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.