National Mall monument to the inventor of the screw propeller.

A centuries-old stone pagoda from Japan stands among cherry trees beside the National Mall Tidal Basin.

The Byzantine, pre-Columbian, and medieval art at this stately mansion are some of the most under-appreciated collections in D.C.

What was once a presidential estate is now an exotic menagerie and home to the Budweiser Clydesdales.

A stellar example of Art & Crafts architecture, and a movie set to boot.

Dedicated to the man who created the first radio wave communication system.

The house where Lincoln drafted the Emancipation Proclamation.

A terrace reminiscent of Rome's Spanish Steps is tucked away in a little park in Washington, D.C.

A secret greenspace hides atop a Capitol parking garage.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

Art deco landmark on the outskirts of Washington, D.C.

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

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

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

This 19th-century windmill was moved, stone by stone, in the middle of Kansas.

This bird statue was created to mark the site of a radio transmitter.

A Kansas nature preserve protecting the plants and animals that once stretched across central North America.

The holiday spirit lingers year-round in the "Christmas City of the High Plains."

Small plaque marks the spot, but the true center is located about half a mile away on a private pig farm.

This lesser-known geographic marker was the reference point for all surveys of the continent for 75 years.

The 55-pound trichobezoar was removed from the stomach of a cow.

One of the Eight Wonders of Kansas and the first official National Natural Monument these stark formations look like nature's Stonehenge.