This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

A small granite block at this monument's base is the only part of Lincoln's Tomb outside of Illinois.

A local prank turned town icon.

The oldest farmer's market in America is so ancient it was approved by the King of England.

A diorama of the Civil War, fought by cats.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

A winding district gerrymandered into the shape of a mantis.

Electronic inventions that resulted in products and systems we use every day are on display in this labor-of-love museum.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

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

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

Home to items never before seen by the public.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

Look closely and you’ll notice that the color changes a third of the way up the tower.

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

Decades before the scandal, this staircase on the river was a literal "water gate."

The whole world in one water tank.

Collecting 700 years of mechanical death-dealing, the NRA's sprawling gun museum is a revealing testament to the American obsession with armament.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.