This is the grave of Andrew Carnegie, self-made man, steel capitalist, and terrible human who tried to buy love for his many, many sins, especially at Homestead, by building libraries around the country. Over half the towns in Pennsylvania rejected his libraries because they knew it was blood money from the dead bodies of his steel workers.
Andrew Carnegie is buried in Sleepy Hollow Cemetery, Sleepy Hollow, New York. Oddly, one can throw a baseball from his grave and hit the grave of Samuel Gompers. Why they are buried not only in the same cemetery, but right next to each other, I have no idea.