The Church of Saint Charles at the Four Fountains, designed by the architect Francesco Borromini (1599-1667) and was his first independent commission.
It is an iconic masterpiece of Baroque architecture, built as part of a complex of monastic buildings on the Quirinal Hill for the Spanish Trinitarians, an order dedicated to the freeing of Christian slaves. He received the commission in 1634, under the patronage of Francesco Cardinal Barberini whose palace was across the road.
However, this financial backing did not last and subsequently the building project suffered various financial difficulties. It is one of at least three churches in Rome dedicated to San Carlo, including San Carlo ai Catinari and San Carlo al Corso.