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.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

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

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

A rotating cast of guys and dolls in front of a Washington, D.C. building.

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

The discovery site of the "Capitalsaurus," the official dinosaur of Washington, D.C.

‘Bush the old fire dog died of poison July 5th, 1869. RIP.’

This unique historical monument features large concrete spheres designed to resemble fallen stars.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

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

After his presidency, George Washington planned to live only a few blocks from the Capitol building.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

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

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

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

A much-maligned monument to teetotalism.

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

At 207 feet, one of the world's longest continuous escalators.

The United States Capitol's former columns still stand.