A memorial to a shareholder activist feared by CEOs around the United States.

Senators used to relax in the nearly forgotten marble tubs now hidden in the U.S. Capitol Building's basement.

A diminutive plaque recalls the treetop sniper who almost killed Abe Lincoln.

Cold War intelligence agents monitored communist embassies from an attic in a former pigeon coop.

More than 500 unique and specially designed cases collected by D.C.'s "Harmonica Case Man."

A building shaped like the Army Corps of Engineers logo, because why not?

Disks are rolled out onto the south lawn to absorb the impact of Marine One's wheels like giant coffee coasters.

The early data processor factory founded in Washington for the 1890 U.S. Census went on to become IBM.

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

During Prohibition, the U.S. Congress had an "official" bootlegger, with his own Capitol Hill office.

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.

The towering figures were created from the cemetery's fallen old-growth trees.

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

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

It was once the base for a series of domestic terror attacks.

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

They sort through millions of dollars worth of diplomatic gifts on behalf of the government.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

The first presidential bomb shelter was located in an old vault under the Treasury, connected to the White House via tunnel.

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.