Romans call this church San Carlo because of its diminutive size. In fact, it could easily fit into one of the pillars that supports the dome of St Peter's. Carried out according to Borromini's design, it has a beautiful oval-shaped dome brightened by hidden windows. Borromini's hand is evident in all of the detail: the confessionals that mirror the architecture of the church for example, or the wrought-iron well in the middle of the cloister. At the main altar, the French artist Pierre Mignard portrays San Carlo Borromeo in an altarpiece. The vestry holds another painting of the saint in adoration of the Trinity by Orazio Borgianni. Do not miss the perfectly proportioned and harmonious cloister.
- Nearest Train: Barberini Fontana di Trevi