The church of Sant' Ignazio di Loyola a Campo Marzio was built in 1626 and dedicated to Ignatius of Loyola, the founder of the Jesuit order, who had just been canonized. It is the church of the adjacent Collegio Romano.

Responsible for the undertaking was cardinal Ludovico Ludovisi . The design is by Carlo Maderno and other artists, and was carried out by Orazio Grassi.

The Dome of Sant'Ignazio

The church is best known for its trompe l'œil painting (1685) by Andrea Pozzo . When standing on a golden disc in the floor of the main nave, the ceiling looks quite natural. From anywhere else in the church it looks quite distorted. From the alter it looks so out of proportion that one might wonder that it seemed real from the entrance. The painting includes an entire trompe l'oeuil dome. It is said that the residents of the neighbourhood where Sant' Ignazio was built didn't want a rather large dome blocking their sun.

The paintings represent the admission of Ignatius into paradise. He is welcomed by Christ and the Blessed Virgin . The figures around him represent the four continents.

Scenes from the life of St Ignatius in the apse are also by Pozzo. They depict for instance the defence of Pamplona, where St Ignatius was wounded.