The tunnel under the Capitol Building where Congress takes out its trash.

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

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

Disks are rolled out onto the south lawn to absorb the impact of Marine One's wheels like giant coffee coasters.

An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

An ear-piercing buzzer calls lawmakers to a vote with a series of long and short rings to form coded messages.

These abandoned waterworks are crumbling into the Potomac River.

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

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

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

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

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

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

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

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

A brass plaque dedicated to a convicted cannibal hangs in the National Press Club, and that's not even the craziest part of the story.

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

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

They sort through millions of dollars worth of diplomatic gifts on behalf of the government.

Obscure Freemasons still live in D.C.’s largest private residence.

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

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

There's an old indoor swimming pool hidden directly underneath the White House Press Briefing Room.

This unacceptably tall building was the real reason for Washington, D.C.'s skyscraper ban.