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

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

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

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

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

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

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

During Prohibition, the U.S. Congress had an "official" bootlegger, with his own Capitol Hill office.

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

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

This grisly headstone doesn’t seem to be resting in peace.

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

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.

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

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

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

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

A promising candidate for the lost rock laid by George Washington was unearthed, but the hunt is still on.

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

These abandoned waterworks are crumbling into the Potomac River.

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.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.