Every drop of D.C. tap water flows through this old waterworks.

An obscure federal monument honors the French diplomat who served as Ambassador to the U.S. during WWI.

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

A small token of gratitude from freezing cold journalists who were given a warm haven while covering JFK's inauguration.

A portal into the bricked up canal that runs through the heart of Washington D.C.

Sit where JFK proposed to Jackie or where Nixon dined on meatloaf at this storied pub.

A diminutive memorial marks the site of a successful assassination by a right-wing death squad in America's capital.

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

The school tested mustard gas for the U.S. Army during World War I.

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

Behind an abandoned storefront is an example of pioneering 1930s gas station architecture.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

The early data processor factory founded in Washington for the 1890 U.S. Census went on to become IBM.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

Daily lunch spot for many of Washington, D.C.'s cab drivers.

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

This stately mansion, built in 1787 by America's first Secretary of the Navy, is rumored to be one of the most haunted buildings in Washington, DC.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

When it comes to handsignals (and colonialism) rock always beats scissors.

Before Nixon, "watergate" meant canals.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.