The Helen Black Miller Chapel traces its origins back to 1826, when the Mercer Episcopal congregation was organized as St. John's Church. Initially meeting in churches and private homes, the congregation constructed a chapel in 1883, measuring 24 feet by 51 feet with an 8-by-12-foot chancel, at a cost of $2,000. Consecrated as Grace Episcopal Church, the chapel was built on South Pitt Street on land generously donated by Miss Maria Magoffin of Mercer. The church thrived, and on August 23, 1895, thanks to a gift from Captain Charles W. Whistler, it was relocated to a new site on Venango Street and renamed the Church of St. Edmund the Martyr. In 1973, the Mercer County Historical Society acquired the chapel and moved it back to its current location on South Pitt Street.