The system of air guns are fired off remotely to scare any trespassing avians.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

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

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

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

Literal "money laundering."

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

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

A secret greenspace hides atop a Capitol parking garage.

This statue of one of baseball’s greatest pitchers looks like something out of a sci-fi horror movie.

This taxidermy horse was a Civil War hero.

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

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

After his presidency, George Washington planned to live only a few blocks from the Capitol building.

The 28,000-year-old specimen is remarkably intact.

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

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

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

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

Amid the sprawling Defense Intelligence Agency Headquarters is one of Washington's least accessible museums.

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

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

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

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