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

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

A memorial to a shareholder activist feared by CEOs around the United States.

D.C. once had its own tiny rival to the New York Stock Exchange.

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

The U.S. Navy’s preposterously detailed mini battleship took 77,000 hours to complete.

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

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

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

Corn-inthian columns with a uniquely American take on neoclassical architecture.

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 line of blue paint marks the route of the inaugural parade.

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

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

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

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

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.’

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

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

These abandoned waterworks are crumbling into the Potomac River.

Look closely and you’ll notice that the color changes a third of the way up the tower.

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