This circus town museum recognizes the outstanding clowns of history.

This luxury shopping lane has been protected by its own tiny police force for over a century.

The massive machine creates cracking displays of indoor lightning.

High on a hill overlooking Los Angeles lives a world famous, high power conical Tesla Coil.

MIT students continue the legacy of beloved professor "Doc" Edgerton through learning by doing.

The only arched bridge made of stone on the entire Mississippi River.

This old residential building was once the largest flour mill in the world.

A propulsion engine testbed that paved the way for the Space Shuttle launch sits without recognition at this rocket center.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

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

A fantastic array of trays and cables once whisked books over to the Capitol at 600 feet per minute.

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.

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

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

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

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

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

The most decorated dog of World War I is preserved in the Smithsonian.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

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

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