The Friends of Zion Graveyard bought the site in 2017.
“We’ve spent five years clearing it, uncovering graves, researching the relatives, and finding the grave of Mary Ann Rawson and the Read family,” said Ms Rea.
“We’ve got both the chapel and the graveyard open. The chapel’s open on Saturday and the graveyard’s open on Sunday, so we can tell the story of this remarkable family and the community.”
Mary Ann Rawson was the daughter of Joseph and Elizabeth Read who owned Wincobank Hall and had inherited Sheffield Smelting Company, later Thessco, from Joseph’s father.
She was later married to banker William B Rawson.
Upper Wincobank Chapel was the church of the Read family, who were non-conformist Christians.
“Mary Ann’s parents saw Wincobank as an ideal conference centre and they used to get all the travelling speakers that came through,” said Ms Rea.
“The radical speakers and thinkers of the day came to Wincobank Hall and would bring their friends together.
“They had missionaries, William Wilberforce, David Livingston’s father-in-law Robert Moffat, and later on Frederick Douglass, who was a freed slave from the West Indies came to speak here,” she said.
Upper Wincobank Chapel will be open from 12:00 BST to 16:00 on Saturday, with guided tours around the building and talks about the bicentenary of the Anti-Slavery Society.
A guided walk up Wincobank Hill will take place in the afternoon at 14:30 and Zion Graveyard in Attercliffe will be open from 12:00 to 16:00 on Sunday.