The main altar is a large Baroque composition, with four fluted Corinthian columns in paonazzetto marble forming two pairs. The altar is dedicated to St John of Matha, and the altarpiece shows The Trinity with St John of Matha (1971) oil on canvas by Aronne Del Vecchio. The altar 'pro populo', installed for Mass celebrated facing the people, is on a pedestal bearing the Trinitarian cross.