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.

A remote horde of architectural treasures fit for Indiana Jones.

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

Two dozen pinball games hidden away inside a most unlikely location.

A Civil War Museum with some notable medical antiques.

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

The final resting place of the tragic king and queen of the Jazz Age is tucked away in a small Maryland graveyard.

This abandoned sea fort has become an accidental bird sanctuary.

A cave on the Maryland border where civilians took refuge during the bloodiest battle of the Civil War.

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

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

Ship skeletons haunt Baltimore's waterways.

This dig site outside D.C. is known for its exceptionally high density of baby dinosaur fossils and dinosaur eggs.

Despite violent work crews and massive delays this abandoned canal tunnel was built to last into the modern day.

A blank headstone topped with a pile of pennies marks the final resting place of the infamous assassin.

This English-inspired Maryland garden is home to acres of opulent plant life including bushes shaped into an entire fox hunt.

The land is home to swimming ponies and a legendary 18th-century treasure.

A priceless collection of the Nation's cryptologic history.

A hidden alley in urban Baltimore is a haven for graffiti artists.

An eerie, decaying ghost town destined to fade into the forest.

This beloved Baltimore spot features caged dolls, a giant Pez collection, and many, many mannequins.

Large tower used for simulating radiation of Hiroshima bomb and the tallest object ever relocated.

This Stonehenge-inspired solar calendar stands alongside a landfill, in the middle of the Nevada desert.