Little did a museum know, they possessed the last-known lunch wagon in existence.

The only surviving prototype for Buckminster Fuller's house of the future.

A sealed test tube said to hold Thomas Edison's dying breath was given to the inventor's friend and mentee, Henry Ford.

The system of air guns are fired off remotely to scare any trespassing avians.

This pharmacist and his patient greet visitors to the National Community Pharmacists Association.

Parking garage where Bob Woodward met Watergate source "Deep Throat."

The rogue roots are gradually consuming some of the historic marble grave markers.

Though his role as the inventor of baseball may be up for debate, fans still festoon Doubleday's grave with baseballs.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

A battleship’s mast sits atop a turret-like memorial, commemorating those who lost their lives in one of the precipitating events of the Spanish-American War.

Decades before the scandal, this staircase on the river was a literal "water gate."

Engraved in stone here are the signatures of everyone who signed the Declaration of Independence.

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

Ruins from the Parthenon and petrified wood line the interior of one of the world's most famous monuments.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

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.

The most decorated dog of World War I is preserved in the Smithsonian.

This taxidermy horse was a Civil War hero.

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

The story behind this beloved toy—named for Theodore Roosevelt and owned by his grandson—is more complicated than you might guess.

This large garden vase urn has nothing to do with the seventh U.S. President—it was designed by one landscape designer to honor another landscape designer's contributions to the National Mall.