This unique historical monument features large concrete spheres designed to resemble fallen stars.

Parking garage where Bob Woodward met Watergate source "Deep Throat."

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

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.

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

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

The most accurate timepiece in the world.

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

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

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

A wondrous old library overlooking the nation's capital.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

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

"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!”

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

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The site of the climactic scene from the classic horror film is now a historic landmark.

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

An 18th-century townhouse that once hosted guests of the president.

Home to items never before seen by the public.

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

The "lovely red Vega" of the legendary record-settling pilot.

When it comes to handsignals (and colonialism) rock always beats scissors.

National Mall monument to the inventor of the screw propeller.