Guidonia Montecelio, commonly known as Guidonia, is a town and comune in the Metropolitan City of Rome Capital, Lazio, central Italy. The municipality of Guidonia Montecelio, formed by the main towns of Guidonia and Montecelio, lies to the north-east of Rome, some kilometres from the Grande Raccordo Anulare - a ring-shaped motorway which forms a ci…Guidonia Montecelio, commonly known as Guidonia, is a town and comune in the Metropolitan City of Rome Capital, Lazio, central Italy. The municipality of Guidonia Montecelio, formed by the main towns of Guidonia and Montecelio, lies to the north-east of Rome, some kilometres from the Grande Raccordo Anulare - a ring-shaped motorway which forms a circle around the capital. The terrain of Guidonia Montecelio is mainly flat, and the community lies in between the Via Nomentana and the Via Tiburtina.