The fifteenth and sixteenth centuries were a time of unprecedented prosperity of the castle. It was expanded after the great fire of 1413 and at the end of the fifteenth century, Cardinal Fryderyk Jagiellończyk added a new east wing with the residential towers. Construction work continued during the sixteenth century by successive bishops Jan Konarski, Piotr Tomicki, Franciszek Krasiński and Piotr Myszkowskiwho gradually gave it all the features of the Renaissance style. All the activities were led by the Italian architect, Jan Balcer.