Over the same period (1764-1766), Piranesi renovated the church and headquarters of the Knights of Malta on the Aventine for their Grand Prior, Cardinal Giovambattista Rezzonico (1740-1783). He devised a ceremonial piazza with an ornamental entrance screen and transformed the modest façade and interior of S Maria del Priorato into an impressive monument to the Order's military history, subtly overlaid with complex antique symbolism .