This grave marks the passing of a historic Jane Doe whose identity remains a mystery to this day.

Collecting 700 years of mechanical death-dealing, the NRA's sprawling gun museum is a revealing testament to the American obsession with armament.

A derelict bit of transportation infrastructure hidden in the woods.

The United States Capitol's former columns still stand.

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

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

You could be standing at the site of one of D.C.'s most fatal tragedies and not even know it.

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 first purpose-built art gallery in the United States is once again open as a center of craft arts.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

Home to items never before seen by the public.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

The romance of early commercial flight still fills this Art Deco destination.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

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

A cement mixer-turned-kaleidoscope in downtown Norfolk offers different views of the city.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

This statue is dedicated to Grace Sherwood, the last person in Virginia to be convicted of being a witch.

This shifting North Carolina sand dune is an odd little desert surrounded by oceanic forest life.

The Cadillac Ranch for monster truck aficionados.