In the first decades of the 16th century, Bishop Bernardo Clesio had a new residence, called Palazzo Magno ("Grand Palace") built in Renaissance style alongside the old castle.

The last great addition was the so-called Giunta Albertiana, from the name of Bishop Francesco Alberti Poja (1686), with which the Castelvecchio and the Palazzo Magno were united.

[3][4][5][6] The interior halls have precious frescoes, including those in the Torre Aquila ("Eagle Tower"), which are one of the most noteworthy examples of International Gothic art in Europe: they represent the "Cycle of the Months" (15th century) and were made by Mistr Václav (master Wenceslas) from Bohemia.

The walls of Torre del Falco (late 16th century) have frescoes with hunting scenes, also a rare example of German landscape painting in northern Italy.

Girolamo Romanino frescoed, among the others, the loggia in the Lions' Court (Cortile dei Leoni) with typical Renaissance themes, such as mythological or ancient Roman episodes, as well as biblical ones, and others from daily life.