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

Four bald cypress trees in Lafayette Square, across from the White House, mark the southern edge of a 100,000 year old cypress swamp.

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

The most accurate timepiece in the world.

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

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

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

A computer bug so primitive it was an actual insect.

A haunting tribute to pioneering photographer Clover Adams.

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

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

There's a crumbling old mansion inside the Smithsonian National Zoo.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

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

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

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

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

When it opened during the final years of the embargo, all the drinks and cigars were free.

The national park was once a plantation estate.

A nostalgic bibliographic gem.

An Industrial Revolution-era public work that purified water using nothing but sand.

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

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