Sinnai, Sìnnia in Sardinian language, is a comune of the Metropolitan City of Cagliari in the Italian region Sardinia, located about 12 kilometres …Sinnai, Sìnnia in Sardinian language, is a comune of the Metropolitan City of Cagliari in the Italian region Sardinia, located about 12 kilometres northeast of Cagliari. Sinnai borders the following municipalities: Burcei, Castiadas, Dolianova, Maracalagonis, Quartucciu, San Vito, Settimo San Pietro, Soleminis, Villasalto, Villasimius.