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

The most accurate timepiece in the world.

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

It was once the base for a series of domestic terror attacks.

There's a crumbling old mansion inside the Smithsonian National Zoo.

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

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

The house where John Wilkes Booth conspired with his co-conspirators.

Largest Roman Catholic church in North America.

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

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

A nostalgic bibliographic gem.

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

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.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

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

Home to items never before seen by the public.

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

Collect holy water from a Bronx grotto.

The abandoned ruins of America's first private zoo are open for exploration in the Catskills.

A gigantic 10-foot tall stone man.

The great American road trip, but smaller.

This lovely little pond is named after the hundreds of soldiers' corpses that were rolled into the waters during the French-Indian War.

This throwback amusement park is home to rides and unique storybook figures from the past.