Upon entering the church one is struck by the extent of the nave which ends in the presbytery. Three arches on each side of red marble, supported by columns resting on great pillars, giving access to the side chapels. Some of them retain the original simple ornamentation (architectural paintings, pictorial contribution limited), according to the principles of austerity of the Company; others are more rich in marbles, altars with columns and pediments, domes painted fresco: the latter were under the patronage of noble Roman families who financed the ornamentation. In the paintings of the presbytery are illustrated key moments of the vocation of St. Ignatius and the beginnings of the Society. A. Well executed frescoes in two phases, from 1685 to 1688 and from 1693 to 1701. In turn evokes the siege of Pamplona, episode the origin of the vocation of Ignatius. Inigo, wounded in the leg during the heroic resistance against the French, transported in the castle of Loyola after the inevitable surrender, he was forced to stay in bed for a long time; during those months began to read books of religion, in particular a translation in Spanish of the Life of Christ of Ludolph of Saxony and the Golden Legend of Jacopo da Voragine. After his recovery (however, remained lame for life) went to Montserrat where laid aside his weapons of soldier at the foot of the Virgin to dedicate himself from that time to the service of Christ. In Paris he finished his theological studies and founded the Society of Jesus with his first companions; in Venice in 1537 and was ordained a priest in Rome, in the Basilica of Santa Maria Maggiore, on Christmas night in 1538 he celebrated his first Mass; the altar of the Virgin of the Basilica of San Paolo solemn vows April 22 1541. It ‘clear the presence of Mary in the spiritual experience of Ignatius: She plays a mediating role between God and men, always on the side of the humble and the poor, inspired the promotion of justice. A. Well celebrated the attention of the Saint to the needy in the fresco of the apse, representing Ignatius who takes care of the plague victims. In the three frescoes in the apse, which are as large plates in gilded frames, the painter has represented three important moments of the life of the Society recently founded. At the center represents the vision that the Saint had in The Retort, suburb of Rome: Christ assures him his help in the work of the Society. The Lord’s words are written on the shield above the altar: Ego Vobis Romae Propitius I was (I shall be propitious to Rome). Since Christ-sun radiates a light against which stand out the figures of Ignatius and companion, in the empty space of ecstasy, bounded by the glory of the angels around the Father. The Holy, referring to this vision, he wrote in his diary: The pilgrim (the name that was given) saw so clearly that the Father had placed him with Christ. The descriptive details are minimized, only the Pyramid alludes to Rome. In the right pane Ignatius welcomes Order Francis Borgia, who will be the third Superior General of the Jesuits; in the left pane Ignatius sends Francis Xavier in the Indies. And ‘the remarkable perspective effect obtained by the painter: the wall seems polygonal apse, while in reality it is concave.