One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

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

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

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

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

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

The "lovely red Vega" of the legendary record-settling pilot.

The most accurate timepiece in the world.

The oldest continuously operating fish market in the United States.

The national park was once a plantation estate.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

Largest Roman Catholic church in North America.

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

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

A nostalgic bibliographic gem.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

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

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The site of the climactic scene from the classic horror film is now a historic landmark.

These flying foxes dangle from the trees around the library like fuzzy black fruit.

Bronze statues honor the brave explorers who passed through this Antarctic gateway.

Sweden's "good old days" painstakingly re-created in a model village.

It houses the remains of a 17th-century version of the Titanic.