Hall joined the
York Archaeological Trust in 1974 as excavations supervisor. He eventually held the position of director of archaeology and deputy director of the trust. At the same time, Hall was a
lecturer in the Department of Continuing Education at the
University of Leeds. Hall conducted pioneering research on
Scandinavian York and helped create the
Jorvik Viking Centre. He also conducted research at the Viking town of
Skiringssal (Kaupang),
Norway and suggested that the Scandinavian settlers of York might have originated from that town. Hall was the author of numerous publications on Vikings, on which he was considered an expert. In his writings, he maintained that Vikings were less violent and more advanced than previously believed, and that they have played a significant role in the history of the
British Isles. Hall was a trustee of the Foundation for the Preservation of Archaeological Heritage and on the Council of the
Chartered Institute for Archaeologists, the Executive Board of the
Council for British Archaeology and the Council of the
Society of Antiquaries of London. He was president of the
Society for Medieval Archaeology and of the
Yorkshire Archaeological and Historical Society, and chairman of the Council of the Institute for Archaeologists from 1987 to 1989. ==Marriages and children==