An imposing, much-copied example of late-16th-century Counter-Reformation architecture, this is Rome's most important Jesuit church. The facade by Giacomo della Porta is impressive, but it's the awesome gold and marble interior that is the real attraction. Of the art on display, the most astounding work is the Trionfo del Nome di Gesù (Triumph of the Name of Jesus), the swirling, hypnotic vault fresco by Giovanni Battista Gaulli (aka Il Baciccia), who also painted the cupola frescoes and designed the stucco decoration.

Baroque master Andrea Pozzo designed the Cappella di Sant'Ignazio in the northern transept. Here you'll find the tomb of Ignatius Loyola, the Spanish soldier and saint who founded the Jesuits in 1540. The altar-tomb is an opulent marble-and-bronze affair with columns encrusted with lapis lazuli. On top, the terrestrial globe, representing the Trinity, is the largest solid piece of lapis lazuli in the world. On either side are a couple of sculptures whose titles neatly encapsulate the Jesuit ethos: to the left, Fede che vince l'Idolatria (Faith Defeats Idolatry); and on the right, Religione che flagella l'Eresia (Religion Lashing Heresy).

The Spanish saint lived in the church from 1544 until his death in 1556. His private rooms, which contain a masterful trompe l'œil by Andrea del Pozzo, are just to the right of the main church.