San Giustino is a comune in the Province of Perugia in the Italian region Umbria, located about 50 kilometres northwest of Perugia on the Tib…San Giustino is a comune in the Province of Perugia in the Italian region Umbria, located about 50 kilometres northwest of Perugia on the Tiber River. In ancient Roman times it was a town named Meliscianum.