Three abandoned missile silos are hiding in plain sight behind a suburban development in Maryland.

A mammoth pair of Civil War artillery guns abandoned out in the forest.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

Giant acorn-shaped 19th century gazebo from which suburban Washingtonians gazed upon the original "silver" spring.

A lawn full of retired spacecraft on display at one of NASA's first research labs.

A star fort along the C&O Canal in western Maryland that protected America in three wars.

The stone marker that Mason and Dixon placed at the eastern end of the famous north-south border they surveyed.

An eerie, abandoned military base engulfed by nature and graffiti is now home to a local park.

This one-room cabin where the young colonel slept during the French and Indian War.

Once America's tallest structure, now a Baltimore landmark.

Politicians, bureaucrats, and military officers gathered in this field near the Capitol to settle their disputes with blood.

This beautiful stone arch bridge wasn't even expected to stand for one day, but people have been crossing it for centuries.

The whole world in one water tank.

One of the oldest anatomical theaters in the U.S. still in use was once the site of an infamous cadaver riot.

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones’ locker.

A labor of love built by local hang-gliding enthusiasts, this ideal launch spot was outlawed by the authorities and has since been largely abandoned.

A pre-Industrial Age iron furnace and the site of a nearly-forgotten piece of Black history.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

This former asylum for Black Americans is haunted by its history of violence and racism.

Live data is transmitted from the Atlantic coast to instantly recreate the ocean waves in this fountain at the NOAA headquarters.

Built by the patriotic residents of Boonsboro in a single day.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.

This scenic Maryland park was the site of one of the worst prison camps of the Civil War.

The longest escalator in the Western Hemisphere takes over three minutes to ride down.