According to tradition this was the site of the villa of the Roman general Pompey, hence the name of this village. In this valley of the Farfa there are many archaeological sites including tombs, remains of villas and the famous bridge over the Farfa. After a dark period, the first news of Mompeo appeared in 817 in the Farfa abbey Registry, which speaks of Fundum Pompeianum.
In 875, the abbot Giovanni allowed a certain Francone to build a fortress on a hill, the current of heart of the historic downtown area. In the twelfth century the feudal lord of Mompeo was Simeotto Orsini, founder of a prominent noble family. In 1646, the estate passed to the Marchesi Naro of Rome and Mompeo reached its peak creating churches and palaces.
Since 1995, the Baron’s Palace has been owned by the City of Mompeo.