At the southern end of Spanish Square is the Palazzo di Propaganda Fide, seat of the Congregation for the Evangelization of Peoples.

The palace was designed by Gian Lorenzo Bernini, who created the main façade; the rest of the building was entrusted to Francesco Borromini, whose style was favored by Pope Innocent X. The building contains the chapel of the Biblical Epiphany, built by Borromini. The palace is extraterritorial property of the Holy See.