The church of Sant’Iganzio di Loyola was built in 1626 in Campo Marzio on a pre-existing structure that has become too small. It was dedicated to Ignatius of Loyola who was the founder of the Society of Jesus, who became a saint a few years earlier. Several architects worked on the building in the first half of the seventeenth century such as: Domenichino, Girolamo Rainaldi, Alessandro Algardi and Cardinal Ludovico Ludovisi financed the work. The history of the building is not very clear, it is known that there was a competition for the appointment of the architect but there are conflicting opinions on the following.
The facade of the church is structured on two orders, in the lower part there are three doors surmounted by tympanums while the central door is flanked by two large columns with Corinthian capitals. In the upper part, aligned with the central door, there is a large window and at the ends of both sides there are large scrolls. It has a Latin cross plan, with a nave, an apse and six side chapels, three on the left and three on the right. Pierre de Lattre, a member of the Jesuits, frescoed the side chapels, the vault of the sacristy and the apse. Andrea Pozzo frescoed the ceiling with a perspective from below, which makes a plane appear superimposed on the real one. It is divided into two orders, one lower and one upper, in which there are columns, arches and entablatures. A beam of light radiates from Christ's side which illuminates Ignatius and the figures of the four continents. Above the intersection between the nave and the transept the image of a dome is reproduced as the real one, for economic reasons, was never built. In the apse are represented the Scenes from the life of Saint Ignatius and a fictitious architecture with four straight columns in a concave surface. On the sides of the presbytery, on the right, there is the Ludovisi chapel with the sepulchral monument of Pope Gregory XV and four stucco statues representing the Virtues; the colossal plaster statue of St. Ignatius is placed in the corresponding space on the left.