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 gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

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

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

There’s a special club house at the top for the bell ringers.

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

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

Go take a picture with the inventor of the daguerreotype photographic process.

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

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

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

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

The most accurate timepiece in the world.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

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

A haunting tribute to pioneering photographer Clover Adams.

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

The most decorated dog of World War I is preserved in the Smithsonian.

The walls of the iconic dome are hollow and have a secret stairway.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The site of the climactic scene from the classic horror film is now a historic landmark.

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