Home to items never before seen by the public.

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

A street in front of NASA's D.C. headquarters has been named in honor of the Black women who were essential to early spaceflight.

A computer bug so primitive it was an actual insect.

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

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

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

A spectacular tribute to statesman and philanthropist Andrew Mellon.

A much-maligned monument to teetotalism.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

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

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

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

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

This unassuming passageway played a key role in one of the most important events in U.S. history.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

Go take a picture with the inventor of the daguerreotype photographic process.

Over the last century, this elegant columned facade has been home to the headquarters of a bank, several nightclubs, and a restaurant.

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

A replica of the famous memorial statue at the Normandy American Cemetery hides in an office building in downtown D.C.

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

A brass plaque dedicated to a convicted cannibal hangs in the National Press Club, and that's not even the craziest part of the story.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”