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

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

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

Washington's iconic carousel has a nice piece of Civil Rights history.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

This hospital fell into ruins after failing to act as the advocate for the mentally ill it was designed to be.

This disastrous New Jersey safari park saw animal attacks, escapes, and disease before being abandoned.

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

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

A diorama of the Civil War, fought by cats.

A dramatic, 360-degree recreation of Pickett's Charge in the Civil War.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

America's first federal monument.

The Pentagon is so large that it was planned like a city, complete with internal highway infrastructure.

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

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.

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

The walls of the iconic dome are hollow and have a secret stairway.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

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

In the basement of the U.S. Capitol Building is a hidden storage room full of ornate floor tiles leftover from the 1850s.

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