A swimming hole in the historic industrial quarry that supplied the marble for the Baltimore Washington Monument.

The United States' oldest Episcopal church still in active use.

Home of the physician who set the leg of John Wilkes Booth after the Lincoln assassination.

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

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

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

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 Civil War Museum with some notable medical antiques.

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

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

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

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

This abandoned sea fort has become an accidental bird sanctuary.

After hundreds of years of settlement, this once-bustling fishing village sunk into the Chesapeake Bay.

Ship skeletons haunt Baltimore's waterways.

Walk a trail through a historic Quaker town that outlawed slavery in 1777 and was a major waypoint on the Underground Railroad.

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.

A priceless collection of the Nation's cryptologic history.

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

A local farm's collection of unusual structures from a now defunct storybook amusement park.

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

This free, take-a-book shop seems like a trick but isn't.