1198 - Saint John de Matha and Saint Felix de Valois founded the Order of the Most Holy Trinity and of the Captives in Cerfroid (France), thanks to the Bull of Approbation of Pope Innocent III, who gave them the church dedicated to Saint Thomas in Formis in Rome, on the Celio hill, between the Colosseum and the Basilica of Saint John Lateran.

14th century - After the expansion of the Order during the Middle Ages in France, Spain, Portugal, England, Scotland, Italy and the Middle East, the socio-political and ecclesial situation, including the Western Schism, slows down its growth, many religious die and the property is expropriated, including St. Thomas in Formis.

16th century - St. John Baptist of the Conception undertakes the reform of the Order, giving rise to the Order of the Discalced Trinitarians.

1599 - Pope Clement VIII gives ecclesial validity to the Congregation of the Reformed and Discalced Friars of the Order of the Most Holy Trinity. In the same year Francesco Castelli, known to history as Francesco Borromini, is born.

1612 - In Rome, on the Quirinal Hill, near the Pope's summer residence, at a crossroads adorned with four artistic fountains, a convent for the Discalced Trinitarians is erected. San Carlino becomes the seat of the Procurator to the Holy See.

1631 - Pope Urban VIII approves the Order of the Discalced of the Most Holy Trinity, Redemption of Captives, as a religious entity independent of the Trinitarians of the ancient observance. Although the Ministers General will reside in Madrid and the General Chapters will be held in Spain, San Carlino will be the house of the Procurator General.

1634 - The Trinitarian religious commissioned Borromini to build their new house by renovating the small convent they had on the Quirinal; the work was carried out under the patronage of Cardinal Francesco Barberini, who lived in a nearby palace. The church was dedicated to Saint Charles Borromeo, an Italian cardinal canonised a few years earlier. Saint Charles of the Four Fountains was to be one of the masterpieces of Baroque.

1635 - Construction begins on the cloister and the convent, including the library.

1638 - Construction of the church begins.

1644 - Construction of the cloister, church and convent is completed and the fau00e7ade is begun.

1667 - Borromini dies; the works are continued by his nephew Bernardo Borromini.

1680 - The decoration of the fau00e7ade and the bell tower is completed, as well as the remodelling of some rooms.