The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The "lovely red Vega" of the legendary record-settling pilot.

Washington's iconic carousel has a nice piece of Civil Rights history.

Perhaps the most scandalous statue of America's first president.

Moscow's most popular cemetery includes the graves of numerous cosmonauts.

Former headquarters of the KGB.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

World's largest bell sits on the grounds of the Kremlin in Moscow.

19th-century scientists would make the pilgrimage here to verify the precision of their measuring sticks.

The handiwork of a underdog clockmaker who solved an impossible problem for an Empire, and forever revolutionized seafaring.

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

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

This one has sailed five times as far as Sir Francis Drake's famous ship.

Scattered throughout London are ancient remnants of the city's former bounding wall.

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

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.

This luxury shopping lane has been protected by its own tiny police force for over a century.

Charles Babbage's proto-computer, painstakingly brought to life.

Eighty million natural history specimens call this gargantuan museum home.