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

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

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

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

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

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

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

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

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

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

These recently uncovered walls are all that's left of Washington, D.C's first defense contractor.

The institution is sitting on a goldmine of 21,000 paints, varnishes, pigments, and primers preserved for posterity.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

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

The most accurate timepiece in the world.

A haunting tribute to pioneering photographer Clover Adams.

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

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

Obscure Freemasons still live in D.C.’s largest private residence.

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

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

The house where John Wilkes Booth conspired with his co-conspirators.

A computer bug so primitive it was an actual insect.

This leafy estate is worth $18 million and is so grand it has two mailing addresses.