This four-story steel sphere in Maryland was used to test biological weapons.

This hidden treasure provides a charming access point along the south side of Baker Park.

Rumors persist that a bottle of whiskey is sealed within this Demijohn-shaped adornment.

Historic barracks utilized during both the Revolutionary War and the Civil War.

A Civil War Museum with some notable medical antiques.

According to local history, this cast-iron canine was nearly melted down for bullets during the Civil War.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

The antique hotel still has a jail in the basement, though the cockfighting ring is long gone.

The former home of Dr. E.B. Henderson, also known as the "Father of Black Basketball."

This monument traces the segregation line that inspired the first rural branch of the NAACP.

This eye-catching sculpture of rural life seems a bit out of place at a suburban intersection in front of a car dealership.

This "castle" is actually a limestone and quartz formation hidden along a trail.

Remnants of a wall built to separate Black residents of Hall's Hill from a newly built subdivision are a grim reminder of segregation in 20th-century Virginia.

These figures float and flutter in this fountain crafted by famed Swedish sculptor Carl Milles.

The well-preserved remnants of a bridge that once made up a WW1-era military railroad.

Home to a 27 room house, this estate was crafted by Black entrepreneur Olander Banks Sr.

The only remaining African American schoolhouse in northern Virginia is now a museum dedicated to formerly enslaved people.

Every plane, auto, and bicycle in this collection is kept in working order and are regularly demonstrated to the public.

A historic ruin just 20 feet away from a busy highway onramp.

A luxurious 1880s hotel with its fair share of Tiffany stained glass, Edison electricity, and of course, ghosts.