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.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

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

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

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

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

A super-sized promotional trick that is now a D.C. landmark.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

The famous abolitionist’s preserved estate is one of Washington's finest monuments to its great Black citizens.

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

The national park was once a plantation estate.

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

There’s a hidden military meme engraved on the World War II Memorial.

The oldest continuously operating fish market in the United States.

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

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

Housing the National Women's Party since 1929, this historic house is now a monument to the fight for gender equality.

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

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

Currently housing a corporate bank branch this building at the southern tip of Manhattan was once the gateway to luxury vacationing.