James of Saint George

Master James of Saint George (c. 1230 – 1309), also known as Master James of Savoy and in French Maitre Jacques de Saint-Georges d'Espéranche, was an architect from Savoy, described by historian Marc Morris as "one of the greatest architects of the European Middle Ages".

He was responsible for designing many of Edward I's castles, including Conwy, Harlech and Caernarfon (all begun in 1283) and Beaumaris in Anglesey (begun 1295).

Early records seem to indicate that his father, Master John, was a master mason who worked on castles in Savoy in the 1260s. These castles included his first at Yverdon les Bains. The "St George" is believed to be a reference to the castle of Saint-Georges-d'Espéranche, located southeast of Lyon. Edward I probably met Master James of St George whilst returning from Crusade and visiting Savoy in 1273. It was 25th June 1273 that King Edward I of England visited Saint-Georges-d'Esperanche so that his great nephew Philip I, Count of Savoy might pay homage to him in fulfilment of an earlier agreement on Alpine tolls

Historian and Author A. J. Taylor uncovered what had been a mystery for centuries in discovering the Savoyard origins of James, that Jacques de Saint-Georges d'Esperanche and Master James of Saint George were one and the same man. Taylor travelled from Wales to Savoy noting for the first time the origins of the Welsh works in Savoy. Taylor citing the garderobes at La Bâtiaz Castle, the windows at Chillon Castle along with the town walls at Saillon as examples

...
Wikipedia