Malcolm Hislop is an independent researcher and author, with a background in the archaeology of buildings and a special interest in the medieval period. His early research was based around the career of the Durham master mason John Lewyn, one of the most prolific castle builders of the fourteenth century. He maintains a keen interest in the process of medieval building design and construction. His previous books include Medieval Masons, John Lewyn of Durham, How to Build a Cathedral, How to Read Castles and Castle Builders.