 Edward placed William of Wykeham in overall charge of the rebuilding and design of the new castle and whilst work was ongoing Edward stayed in temporary accommodation in the Round Tower . Between 1350 and 1377 Edward spent £ 51 @,@ 000 on renovating Windsor Castle ; this was the largest amount spent by any English medieval monarch on a single building operation , and over one and a half times Edward 's typical annual income of £ 30 @,@ 000 . Some of the costs of the castle were paid from the results of ransoms following Edward 's victories at the battles of Crécy , Calais and Poitiers . Windsor Castle was already a substantial building before Edward began expanding it , making the investment all the more impressive , and much of the expenditure was lavished on rich furnishings . The castle was " the most expensive secular building project of the entire Middle Ages in England " . 
