Re Magi (Kings Magi) is the 17th century collegiate church of the Palazzo di Propaganda Fide.
Palazzo di Propaganda Fide
The Palace of the Propagation of the Faith, which lies a short distance from the Spanish Steps, was begun by Gian Lorenzo Bernini (1598-1680) for Pope Urban VIII (r. 1623-44), but completed by his arch-rival Francesco Borromini (1599-1667).
The Congregation for the Propagation of the Faith (Sacra Congregatio de Propaganda Fide) was founded by Pope Gregory XV (r. 1621-23) in 1622 to arrange missionary work on behalf of the various religious institutions. In 1627, his successor Pope Urban VIII (r. 1623-44) established a training college for missionaries, the Pontificio Collegio Urbano de Propaganda Fide.
The main facade of the palace was created by Bernini, but when Pope Urban VIII died in 1644 he was succeeded by Innocent X (r. 1644-55), a pope who preferred the work of Borromini. And so the commission was handed over to the new man, who went on to create the much more exciting and dynamic side facade. The palace was completed in 1667, the year of Borromini's death.
Vault
Borromini also designed the exciting Church of Re Magi (Kings Magi), which is part of the palace. Work began in 1644, but was not entirely completed when Borromini died.