The church and the convent located a the Four Fountain cross-road was designed by Borromini in 1634. The church, dedicated to S. Carlo, is very small and it is also known as “S. Carlino.” Noteworthy the oval dome with its ingenious little lanterns. Finished in 1667, the façade is one of Borromini's last works. In the crypt a small curved chapel reserved for him remains empty, because he committed suicide in 1667.