The patron saint of Monterotondo is Saint Michael the Archangel, celebrated on 29 September.
The fief belonged from the 12th century to the Orsini family, who held power there until the 17th century and whose most glorious moment was the 1468 marriage of Clarice Orsini to Lorenzo the Magnificent. In 1626, owing to financial difficulties, the Orsini sold the fief to the Barberini, who had it raised to a duchy in 1627 and restored the palace with new frescoes and stuccowork. In 1621 the Council of Forty had approved the construction of a new parish church, work on which began after the symbolic planting of a cross in 1629: the duomo was thus built in 1639, becoming the cathedral of the bishop of Sabina, and in 1641 received a visit from Pope Urban VIII, who donated precious sacred vestments and an eleven-quintal great bell to the church. In 1845, thanks to the interest of Cardinal Luigi Lambruschini, the duomo received a visit from Pope Gregory XVI, who raised it to the rank of minor basilica.
