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

It may look like no more than a full-scale model, but every part of this full Space Shuttle stack had a working role in aviation history.

This 12-foot-tall T-rex is the largest K’Nex skeleton sculpture in the world.

Bananas are often left for the first monkey America ever recovered alive after being launched into space.

Go take a picture with the inventor of the daguerreotype photographic process.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

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

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

Stepping away from the glitz of mobsters and casinos to learn about the other history of Vegas.

This incredible collection of vintage pinball machines can be played at 25 cents a pop.

These banned cigarette vending machines now sell little pieces of pocket-sized art.

A giant open-air sculpture made of over 200 full-sized boats.

An overlooked monument to the celebrity gangster who helped put the sin in Sin City.

One of the world's tallest Ferris wheels takes visitors high above Las Vegas in a spinning party room.

An exotic wildlife habitat right off The Strip.

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

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.

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

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

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

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

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

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

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.