A secret greenspace hides atop a Capitol parking garage.

This gravestone and its inscription inspired a movement that has spanned generations and saved countless lives.

This brick-lined pedestrian walkway was once a railway tunnel used during the Civil War.

FDR's Art Deco hospital tower was hopelessly inefficient.

This home is steeped in history from, George Washington to George Corwin, High Sheriff during the Salem Witch Trials.

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

The system of air guns are fired off remotely to scare any trespassing avians.

Legend says this public grazing area hasn't been plowed for thousands of years.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

Single runway interrupted by a busy road that cuts across its middle.

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

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

She stares out across six lanes of traffic, clutching a musket and infant with determination.

The spot where three Protestant clergymen were burned at the stake during the reign of "Bloody Mary."

The medieval woodcut-style artwork chronicles life in medieval London.

The famous polar explorer stands outside the Royal Geographical Society's headquarters.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

D.C. once had its own tiny rival to the New York Stock Exchange.

After his presidency, George Washington planned to live only a few blocks from the Capitol building.

Proto-CIA agents trained with grenades in the sand traps and fired machine guns from the fairways.

This Norman castle was once the site of a Victorian-era prison, and now exists as a luxury hotel.

This historic pub is a hidden gem for fans of Lewis Carroll.

The 28,000-year-old specimen is remarkably intact.