The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

This forgotten boat elevator was an engineering marvel in its heyday.

A derelict bit of transportation infrastructure hidden in the woods.

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

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

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

Need a hardcopy of the 50-title Code of Federal Regulations? This is the place.

A historic ruin just 20 feet away from a busy highway onramp.

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

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.

A wondrous old library overlooking the nation's capital.

An overlooked tribute to one of the most important peace deals in American history.

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

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

A building shaped like the Army Corps of Engineers logo, because why not?

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

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

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

Helen Keller once broke ground on this historic center for the study of technologies to benefit the hearing impaired.

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

This robust fence in front of a historic Georgetown home is likely made from hundreds of recycled Revolutionary War firearms.

More than 500 unique and specially designed cases collected by D.C.'s "Harmonica Case Man."

This grand gothic brewery has been pumping out suds for over a hundred years.