The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

Need a hardcopy of the 50-title Code of Federal Regulations? This is the place.

The school tested mustard gas for the U.S. Army during World War I.

This nine-story building is the oldest standing skyscraper in D.C.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

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

The fountains of the U.S. Navy Memorial are annually salted with water from the Seven Seas as part of a nautical ritual.

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

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

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

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

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

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

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

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

100 years later, they're still down there.

Daily lunch spot for many of Washington, D.C.'s cab drivers.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.

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

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

Art deco landmark on the outskirts of Washington, D.C.

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