Monterotondo overlooking the Tiber valley was in the past the ancient Sabine city of Eretum, placed at the end of the Via Nomentana, as related by Virgil in the Aeneid.
With the arrival of the Barbarians, in the Middle Ages the core of the modern city was formed around a rock shelf on Monte della Ginestra, and roads followed circular lines. This first peoples were under the protection of the Abbey of Farfa, and for the first time appears the name ‘Campus Rotundus’.
From the thirteenth century it passed under the control of the Orsini family, which historically has been represented by two popes (Celestine III and Nicholas III). The highlight of this family occurred when Clarice Orsini married Lorenzo the Magnificent in Florence, who was the protagonist of the Italian Renaissance, and their son would become pope with the name of Leo X. The Orsini transformed the castle into a Renaissance palace.
With Pope Urban VIII Barberini, from 1626 Monterotondo passed under the control of the Barberini family and became a Duchy that produced great works of town planning and the Duomo.
After the Barberini came the Grillo family and finally the Boncompagni.
Monterotondo hosted Giuseppe Garibaldi on his arrival in Rome. In 1915 Monterotondo was seriously damaged by the earthquake of Avezzano. During World War II it was the headquarters of the Armed Forces and massively attacked by the Germans.