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

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

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.

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

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

The preamble to the U.S. Constitution written entirely from vanity license plates hangs in the Smithsonian museum.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

This taxidermy horse was a Civil War hero.

This statue of the "father of television" stands prominently in the United States Capitol.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

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

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

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

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

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

In 1787, a group of delegates met at this very spot to drink, be merry, and ratify the Constitution of the United States.

Museum houses an impressive display of the origin and artistry from the now-quaint invention's history.

A grotesque Fiji merman dwells within this traditional Dutch-style building.

The historic home still shows the scars from a little run-in with the British in 1813.

What began as an art installation is now the private drinkhaüs for a brewery's employees.

The final resting place of an unidentified revolutionary soldier sits behind a Virginia church.

This church built atop a gas station promises to "equip you for the next stage in your life’s journey."

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