A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

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

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

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

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

A much-maligned monument to teetotalism.

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.

Washington's iconic carousel has a nice piece of Civil Rights history.

Home to items never before seen by the public.

Look closely and you’ll notice that the color changes a third of the way up the tower.

The National Park Service’s best-kept secret with views that rival any in D.C.

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

Fittingly, America's museum of architecture is itself a magnificently designed old building.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

A line of blue paint marks the route of the inaugural parade.

An overlooked memorial honoring the local Washington residents who died in World War I.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

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

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.