Her sister Joanna left for Florence and Barbara left for Ferrara. Her Wikipedia article with this image is here.
Barbara wears a dress duplicating the one worn by Joanna.
Keywords: 1565, Terzio, Barbara of Austria, Archduchess, Duchess, Habsburg family, Este family, straight coiffure, jeweled hat, jeweled headdress, high enclosing neckline, ruff, French sleeves, cuffs, girdle, vee waistline, A-line skirt, necklace, jeweled pendant chain, jeweled pendant, fan