The 17th century church of Santi Ambrogio e Carlo, better known as San Carlo al Corso, is dedicated to two great bishops of Milan, St Ambrose (died 397) and St Charles Borromeo (1538-84). The church was designed and built by Onorio Longhi (1568-1619) and completed by his son Martino Longhi the Younger (1602-60). Its grand dome, a prominent feature of the Roman skyline, is the work of Pietro da Cortona (1596-1669).
The Baroque interior of this very large church (72 by 54 metres) is sumptuously decorated. The fresco in the vault of the nave depicts the Fall of the Rebel Angels (1677-79) and is the work of Giacinto Brandi (1621-91). The frescoes in the vault of the sanctuary are also by Brandi.
The painting on the high altar is the work of Carlo Maratta (1625-1713) and depicts the MadonnaPresenting of St Ambrose and St Charles Borromeo to Christ. A figure below the feet of Christ holds a tablet bearing a single word Humilitas, the virtue for which St Charles was famous.
The interior of the dome is decorated with a complex design of gilded stucco-work. The Chapel of the Immaculate Conception, in the right transept, was designed by Paolo Posi (1708-76) and completed in 1769. The altarpiece is a copy, in mosaic, of The Immaculate Conception with the Doctors of the Church, a painting by Carlo Maratta in the Cybo Chapel in the church of Santa Maria del Popolo. The two statues depict King David and Judith with the Head of Holofernes; they are, respectively, the work of André Jean Lebrun (1737-1811) and Pietro Pacilli (1720-72). The inscription at the top of the altar proclaims: TV SOLA VNIVERSAS HAERESES INTEREMISTI (You alone have destroyed all our heresies), a reference to the Virgin Mary.
The Chapel of the Blessed Sacrament, in the left transept, is very similar to the one opposite. However it was created less than a century ago, during the reign of Pius XI (r. 1922-39), to celebrate the fiftieth anniversary of the pope's ordination as a priest. The chapel was designed by the Roman architect Cesare Bazzani (1873-1939).
San Carlo al Corso is the only church in Rome to have an ambulatory (a walkway behind the high altar). There you will find a niche with a reliquary containing the heart of St Charles Borromeo, who was canonised on November 1st, 1610 by Pope Paul V (r. 1605-21). It was donated to the church in 1614 by his cousin, Cardinal Federico Borromeo.