Anthropology Professor Mark Auslander, who teaches at Central Washington University, has discovered evidence that slave labor was used in quarrying the red sandstone that was used to build the iconic Smithsonian Castle. And some of those slaves were probably once owned by Martha (Dandridge) (Custis) Washington, wife of George Washington.
The sandstone came from a quarry in Seneca County, Maryland, owned by John Parke Custis Peter, a great-grandson of Martha. Peter inherited some of Martha’s slaves upon her death.
This story adds to the history of buildings in the district, and the involvement of slave labor in their construction. You can read more in the Washington Post.