Once populated by the Falisci, then by the Etruscans, and finally conquered by the Romans, this area has always been characterised by a pastoral vocation and crossed by transhumance trails and rural roads.
Magliano extends in the northernmost part of the Veio Park, which preserves important archaeological evidence of ancient times. The park can be reached on foot or by bicycle, along numerous paths.
In the Middle Ages, the first nucleus of the present town took shape in the locality of 'Il Casale'. The settlement was fortified to protect it against Saracen attacks and later becoming a feud of the Anguillara family.
In the mid-12th century, with the victory of the Ghibellines of Viterbo, the settlement was destroyed and the construction of the new village began in its present location, with successive interventions over the centuries by different owners (Orsini, Cesi, Borromeo, Chigi).
Until 1907, the town was called Magliano Pecorareccio, an indication of the area's vocation for sheep farming.
Still today, every year in spring, the Sagra della Pecora (Sheep Festival) is held.