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

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

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

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

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

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

The trials and tribulations of marking Poe's grave.

Right next to departures—how convenient!

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.

The romance of early commercial flight still fills this Art Deco destination.

A former major munitions plant that has been converted into a sprawling art space.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

The rogue roots are gradually consuming some of the historic marble grave markers.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

America's first public mental health facility.

The final resting place of two (or three) presidents, one vampire, and 18,000 Confederate soldiers.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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

An overlooked memorial honoring the local Washington residents who died in World War I.