A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

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

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

A portal into the bricked up canal that runs through the heart of Washington D.C.

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

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

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

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

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

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.

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

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

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

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

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

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

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.