Senators used to relax in the nearly forgotten marble tubs now hidden in the U.S. Capitol Building's basement.

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

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

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 only place for a truly presidential dram.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

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

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

Home to items never before seen by the public.

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

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

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

This unassuming passageway played a key role in one of the most important events in U.S. history.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

It marks the spooky spot where the bodies of two young boys were found in the 19th century.

A star fort along the C&O Canal in western Maryland that protected America in three wars.

An abandoned stretch of highway, deteriorating next to the operational one.

Berkeley Hot Springs presents to you "the only outdoor monument to presidential bathing."

The antique hotel still has a jail in the basement, though the cockfighting ring is long gone.

A remarkable time capsule of American manufacturing deep in Maryland coal country.

This abandoned asylum was once a state of the art facility before devolving into one of the most deadly mental institutions in American history.