Throughout the fifteenth century, artists continued to elaborate earlier Renaissance trends. Among these was the interest in portraiture, which appears in increasingly varied contexts. Donor portraits and self-portraits were still included in depictions of biblical events; sometimes several family members and other contemporary figures populate the scenes. The frequency and types of individual portraits—equestrian monuments and state portraits, for example—expanded as well. Altarpieces underwent considerable development and by the latter decades of the quattrocento reflected the trend toward combining secular with Christian content. In Mantegna's frescoes for the state bedroom in the Ducal Palace of Mantua, the Renaissance taste for illusionism, evident in the revival of anecdotes about Classical Greek artists that were applied to Giotto, permeates the entire work.