Chiesa di San Carlino alle Quattro Fontane (Church of St. Charles at the Four Fountains), Rome

During the year 1634, the Trinitarians, a Spanish order dedicated to the redemption of Christian hostages from Arab captors, enlisted the talent of Borromini to create a church and convent at the crossroads of Quattro Fontane. This remarkable church, often referred to as "San Carlino", holds profound significance not only as a tribute to Cardinal Carlo Borromeo, canonized in 1620, but also as a testament to Borromini's architectural genius.

Despite its modest dimensions, San Carlino showcases bold curves that infuse the compact space with light and vitality. The ingenious design includes an oval dome and a delicate lantern, demonstrating Borromini's ingenuity. The completion of the façade in 1667 marked one of Borromini's final endeavors.

Beyond the façade, San Carlo reveals further delights to its visitors. The playful inverted shapes in the cloister add a touch of whimsy, while the exquisite stucco work in the refectory showcases the mastery of craftsmanship. A small room adjacent to the sacristy holds a portrait of Borromini himself, donning the Trinitarian cross, serving as a poignant reminder of the artist behind this architectural marvel. Tragically, Borromini took his own life in 1667, and in the crypt, a small curved chapel intended for him remains unoccupied, serving as a solemn tribute.