This church found at via del Corso, has the cardinal and nepot of Pope Pius IV – St. Charles Borromeo, who was canonized in 1610, to thank for its consecration. However, before this came to pass, the church was consecrated in the name of another saint – the bishop of Milan, Ambrose. A church had previously existed in this place, belonging to the Lombard commune, which was reconstructed at the beginning of the XVI century. When Charles Borromeo became saint, The Lombard Confraternity, decided to expand the church, at the same time consecrating it to two great sons of Milan (the full devotion in Italian is Santi Ambrogio e Carlo). The designer of the new church, of which the reconstruction had begun in 1612 – was the infamous due to his swashbuckling lifestyle comrade of Caravaggio – Onorio Longhi. After his death in 1619, works on the church were taken over by his son Martino Longhi (the Younger) – a descendant of a multi-generation family of builders who came to Rome from Lombardy. The architect was aided by his colleagues - Francesco Borromini and Pietro da Cortona. The latter was also the creator of the dome from 1668, and also the one who was responsible for supervising the painters, sculptors and plasterers working in the church. The façade of the church was completed twenty years later. Its maker was surprisingly, Cardinal Luigi Alessandro Omodei, after the design of a renowned Roman architect Carlo Rainaldi, had been discarded.

The interior on the other hand, was being decorated throughout the whole of the XVIII century. Luminous and spacious it has the shape of a Latin cross, over which in the central point a slender, well-lit dome arises. The main fresco of the vault by Giacinto Brandi, depicts, The Fall of the Rebel Angels, and it can be assumed that it foretells the fate of dissenters in faith, meaning advocates of the Reformation. Another of Brandi’s work is also a very good fresco on the top of the apse, showing the scene of the Procession of the Holy Cross, in which Charles Borromeo is participating. In the side naves and in the presbytery we will see allegories of virtues, paintings completed by various second-tier Roman fresco painters (including P. Albertoni, G. Troppa, G. B. Benaschi, L. Garzi, F. Rosa, P. Paolini). The main altar is adorned by a paiting depicting the glory of the saint patrons of the church (Charles Borromeo and Ambrose) accompanied by The Virgin Mary, venerating Christ, one of the most important works of Carlo Maratti. On the other side of the altar (in the ambulatory) there is a small altar with the relics of the heart of St. Charles Borromeo, brought from Milan. Its surroundings are decorated similar to a rococo salon, with paintings and moldings. In the ambulatory there are also monumental figures of saints as well as an interesting, classical tombstone by the classicist sculptor Francesco Righetti.

It is also worth directing our attention to a chapel found at the end of the transept (on the right). It is devoted to the subject of the Immaculate Conception. Completed in colorful marble and bronze it was decorated with a mosaic which is a copy of a painting by Carlo Maratti, found in the Church of Santa Maria del Popolo. The altar is accompanied by statues of heroes of the Old Testament – Judith, sculpted by Pietro Pacilli (1769) and David, created by the outstanding French sculptor Andre Jean Le Brun. The altar on the opposite side, which is very similar, is devoted to the Blessed Sacrament, but it is from the XX century and is almost a carbon copy of the original.