The 18th century convent church of Santissima Trinità degli Spagnoli (Most Holy Trinity of the Spaniards) was built for the Spanish branch of the Ordo Sanctissimae Trinitatis et Captivorum (Order of the Most Holy Trinity and of the Captives), better known simply as the Trinitarians.
The Order was founded in 1198 by St John of Matha (1160-1213). Its mission was to buy the freedom of Christians taken prisoner by Muslim pirates and slave-raiders. This explains the presence of the striking sculpture of the Angel With Two Prisoners by Pietro Pacilli (1720-73), above the entrance.
The church and the adjacent convent were built between 1741 and 1746 by Emanuele Rodriguez dos Santos, a Portuguese architect. The two statues on the concave facade depict St John of Matha and St Felix of Valois.
The ground plan of the interior takes the form of an ellipse. The nave, which has three chapels on each side, is dominated by its beautiful dome. The fresco depicts The Apotheosis of St John of Matha (1748) by Gregorio Guglielmi (1714-73).