Magliano Romano is located on a cliff along the Via Flaminia, one of the Roman consular roads, and its roots are first Etruscan and then Roman. It has never been a large Roman centre but more a staging post. After the passing of the Barbarians, the people gathered in fortress-farms and in the Middle Ages around a thousand came under the control of the Benedictine monks of St. Paul Outside the Walls.
Agriculture and grazing have always been the main features of this centre, which for many centuries has been called ‘Magliano Pecorareccio’ in order to emphasize the importance of the sheep.
In 1200, the village was formed around a castle that was strongly attacked by the papal troops during the struggle between the Guelphs and Ghibellines. Magliano Romano later passed from one feudal lord to another and, in 1862, it came under the control of the Arnaldi who still are the owners of the fortress.