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

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

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

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.

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

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

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

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

The 320-year-old tree that greeted General Lafayette and rerouted an interstate highway.

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

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.

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.

The remnants of a wooden-hulled fleet built and abandoned in WWI, now home to a thriving ecosystem.

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

The site where Poe "in great distress, and ... in need of immediate assistance" likely died.

The trials and tribulations of marking Poe's grave.

A natural rock formation believed to be a cure-all.

One of New York's most iconic authors is strangely honored by this Oklahoma park.

A larger-than-life monument to the overlooked women who braved Western expansion and broke down societal barriers.

The modest childhood home where the baseball legend and Yankees star learned to hit from both sides of the plate.

This 19th-century sugarcane plantation is one of the most well-preserved estates of its kind, including its original quarters for enslaved laborers.