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

A clone of a cloned tree that was so important it allegedly had its own guards.

A historic ruin just 20 feet away from a busy highway onramp.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

The span is crooked and made from two older recycled bridges.

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.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

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

This lovely pocket park is one of the most under appreciated in D.C.

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

The most accurate timepiece in the world.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

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

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

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

A celebrity from the late Cretaceous period.

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

The oldest continuously operating fish market in the United States.

Largest Roman Catholic church in North America.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

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.

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