On the ground floor of the square Castellana tower in the north-eastern corner of the Rocchetta is the treasure room: the Sforza period room in which the documents and valuables of the family were conserved. The room was decorated during the reign of Ludovico il Moro with a fresco by Bramantino depicting Argus, the mythical 100 eyed custodian to symbolically safeguard the treasure. In correspondence with the square tower on the opposite side of the Rocchetta is the Falconiera tower, within which lies Leonardo's Sala delle Asse (Room of the Wooden Boards).