In this article we talk about one of the most beautiful paintings of illusionistic painting (trompe l'oeil) de 600, in particular a painting by Andrea Pozzo, painted on the ceiling of the church of St. Ignatius in Rome. With the advance of 600 desire to open the interior space is extended, especially for the meeting halls of the palaces and churches. The solution of illusionistic painting commissioned by Bernini was for practical reasons, in general, the only feasible in the buildings; and it was also the only possible in existing churches. The painting most spectacular of this type is a fresco by Andrea Pozzo: the allegory of the missionary work of the Jesuits in the church dedicated to the founder, St. Ignatius. Covers the entire ceiling of the nave of which it takes the true prolungandole walls up to the sky by groups of columns supporting entablatures and arches. In the sky and between the columns circling countless figures. It is a real tour de force of architectural perspective that Pozzo himself explained in detail in a treatise on perspective. The ceiling fresco of St. Ignatius is not yet a perfect fusion of painting and architecture, because the illusion only works if there is at the center of the nave, the position from which the photograph was taken here reported.