A UNESCO report on Durham Castle provided this additional information about the bishop: Walcher "purchased the earldom Northumbria and thus became the first of the Prince-Bishops of Durham, a title that was to remain until the 19th century, and was to give Durham a unique status in England. It was under Walcher that many of the Castle’s first buildings were constructed. As was typical of Norman castles, it consisted of a motte (mound) and an inner and outer bailey (fenced or walled area). Whether the motte and inner bailey were built first is unknown".