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

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

Eighty million natural history specimens call this gargantuan museum home.

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

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

Berlin's beloved bear is immortalized at the Museum für Naturkunde.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

A restaurant and observation deck built in a unique broadcasting antenna.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

Started as a kitchen garden, now the second largest botanical garden in the world.

This demon atop the Notre-Dame de Paris looks utterly bored.

The video game-themed street art first popped up in the French city.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

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

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

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

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

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the 20th century.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Florida might be at its most surreal in this museum devoted to the famed Spanish artist.

A luxuriant botanical garden below sea level.