Inhabited by the Falisci, the territory of Monterosi was in Roman times a staging post along the Via Cassia.
The Monterosi name is an obvious compound of "mount" to which you add a second term, probably derived from the Latin "rosa" (pink).
The first mention of the village dates back to 1081, in a document in which Pope Gregory VII assigned it to the abbey of Sant Anastasio.
During the Middle Ages it continued to be part of the possessions of the monastery, except for some periods during which it passed under the control of important families like the Prefects of Vico, Anguillara and Orsini.
In the thirteenth century Frederick II of Swabia, struggling with the Pope, built up a castle in Monterosi; obligatory point of passage for those who moved to Rome, the place became the scene of great events such as the meeting between Frederick Barbarossa and Pope Adrian IV.
Along the route of the old Via Cassia you can still see the shrine of the Fallen, which commemorates the sacrifice of Officer Ettore Rosso and his soldiers. The group is celebrated because it was able to block, exactly at this point, the advance of a German column in 1943.