Manhattan's deadly West Side railroad, which killed hundreds of New Yorkers, is remembered by this simple plaque.

The front yard of an Upper East Side town house hides the last fragment of one of New York's most famous theatres.

Though its celestial ceiling is impressive, the true star is the vast collection of French books.

A mysterious inscription may hold a clue about the "Lost Colony" of Roanoke.

After just one epic test blast, this literal loose cannon proved too explosive for combat.

A white oak with property rights.

The first blast furnace in the United States that used coal and coke fuel instead of charcoal to make pig iron.

Spectacular mineral formations fill these caves, which have been used for everything from smoking meat to stashing illicit liquor.

This harrowing climb along West Virginia's jagged spires is one of the only Via Ferrata on America's east coast.

The only labyrinth within the city of Alexandria.

Little has changed in the way that this mill operates since the 18th-century.

Every autumn, this grove of living fossils erupts in a blaze of brilliant golden-yellow leaves and stinky fruit.

The only remaining African American schoolhouse in northern Virginia is now a museum dedicated to formerly enslaved people.

Born a slave on the Arlington estate, Parks dug the first graves at Arlington National Cemetery, and was buried there, too.

This tree is a living witness to the beginning of the Civil Rights Movement.

The largest cemetery for enslaved people in Loudoun County was almost lost to history, if not for the research of a minister.

Once forgotten and built over, this historic Black cemetery now houses a poignant memorial.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

The oldest arched-covered bridge in Virginia has truly withstood the test of time.

This labyrinthine resting place of Black American leaders has been reclaimed by nature.

Lines from a walking song are etched into a rock in Natural Bridge State Park.

Colorado's oldest church is now home to the largest handmade adobe labyrinth in the world.

A Colorado store that specializes in all things spiritual, metaphysical, and witchy.

Winter and summer solstice aligned sculpture in the middle of nowhere.