A wonderland of caves in eastern Iowa.

An old town theater converted into a celebration of the hobo legacy.

A roadside collection of over-sized iron creations that are a bit more macabre than most.

A burial site located in the middle of a road.

Visitors to this arboretum are greeted by three smiling giants crafted from sustainable materials.

An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

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

An overlooked memorial honoring the local Washington residents who died in World War I.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

One of the most influential presidents in U.S. history wanted only this plain, elegant monument as his lasting memorial.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

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.

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

This statue of one of baseball’s greatest pitchers looks like something out of a sci-fi horror movie.

A super-sized promotional trick that is now a D.C. landmark.

The famous abolitionist’s preserved estate is one of Washington's finest monuments to its great Black citizens.

Outside the Department of Transportation, a collection of artifacts honors the history of how we get around.

A much-maligned monument to teetotalism.

This sandwich shop has a century-old elevator behind a sheet of plexiglass.

The fountains of the U.S. Navy Memorial are annually salted with water from the Seven Seas as part of a nautical ritual.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

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